Once you start down the dark path, forever will it dominate your destiny.
-Yoda (a long time ago)
Updated December 5, 2007.
I had a coversation with my neighbor recently. It went something like this:
Him: "You're running a car tire, aren't you?"
Him: "I've read about that somewhere. It's controversial."
Me: "Not for those of us that are doing it. No controversy at all."
Him: "Well, it can't handle."
Me: "It does."
Him: "It's not safe."
Me: "It is for me."
Him: "It's not tested."
Me: "I've tested it all the way to Alaska and back. A bike tire couldn't have taken the abuse."
Him: "Well, I know it's just not safe. It can't work."
I know better than to argue tires, helmets, or oil with another biker. Put two of us in the same room and ask the question and you'll get 12 different and vehement answers. Still, he did ask...
Me: "I've got a lot of riding experience. It's my bike. I don't have a problem with it. Why should you?"
Him: "I've got a lot of experience too. I just know it can't work."
He's been riding for about 5 years now. He's got a pretty bike. I rarely see it move. We call those "Butt jewelry".
Me: "How many miles do you have on your machine?"
Him: "Almost seven thousand."
Hmmm. I might see the problem here. I've run more miles than that since I changed the oil last time. I've ten times that on this bike alone, and over three times that just on my rear tire...the tire he was telling me "can't work."
I changed the subject and we talked about yards for a while. That's usually a safe topic for neighbors.
Anyway, all that got me to thinking it was time to update this page, as I first put it up when I had only ridden 3000 miles or so on my first car-tire. I've now run over 100,000 or so and so I've added more pictures and information to update my experience.
Okay. This is a rather long-winded treatise on the installation of a car-tire on the rear of a Valkyrie motorcycle. With the size/weight of some motorcycles, as well as a host of new tire sizes and technologies in the car-tire world, there are tires that can fit and perform on the rear of some motorcycles.
I get many questions, lots of curiosity, and even some rather irate email over this subject so I thought I would set down my thoughts, reasoning, and experience with this project so others that may be contemplating it, or wondering why anyone would even try such a thing could know my experience with it.
Note that I have no motivation for justifying what I have done, vindicating myself, or convincing others of the validity of my decisions. All this is my experience and opinion. I assume no liability for my documentation or methods. I will try to be objective in my reporting of this experience, but do note that motorcycle tires are a pet peeve of mine. I will discuss this a bit later.
As of this writing I have put about 42,000 miles (edit 12/5/07...over 100,000 miles now) on car-tires on my Valkyrie in a multitude of extreme conditions. High-speed highway, high-speed rain, wind, dirt/gravel, twisties, congested city, construction, and emergency stops. I'll take some heat for this, but there is NO downside for the experienced rider. The car tire has been superior in every condition. I've found the car-tire to be so far superior to the MC tire for the rear of the Valkyrie that there is no point in my pretending I'll ever go back to the MC tire.
Tires are religion, and in the motorcycle arena and our litigious society are viewed very much as a "dark art" and are seldom discussed rationally. I am not looking to justify my actions or convert anybody. I am seeking to explain what I have tried and why, so those that have an open mind and some experience to go with it can understand. Frankly, like oil choices, I do not feel the emotion and anger often shown over the issue are merited. It's just not that big a deal.
Among VRCC'rs ... putting a car tire on the Valkyrie is known as, "Going to the Dark Side."
This thing's gonna fit?
Oh yeah....it fits!
I will attempt to do this in a FAQ (frequently asked question) format:
What is your experience on motorcycles?
I have been riding for over 25 years on a large variety of machines. I would guestimate (technical term) that I have ridden well over half a million miles. Much of that is in Texas and other southwestern states, but I have ridden all over the nation. I have ridden in rain, hail, snow, mud, gravel/dirt, extreme heat, extreme cold, and many other conditions.
Why would you even consider putting a car tire on a motorcycle?
Motorcycle tires are a pet peeve of mine. I have ridden a lot of miles, and so have a lot of experience with different makes and models of tires on a variety of different machines.
To point out my peeve with motorcycle tires, first I will discuss car tires just a moment:
25 years ago, a tire for my car cost $35 and lasted about 30,000 miles. Occasional failures of tread or bead/such were expected, but not frequent.
Today, a tire for my car costs $90 and lasts 70,000 miles. Failures are unacceptable and very unusual and are covered by extensive warranties. We've tripled the price and more than doubled the miles. In addition the technologies have made them handle better in cornering, wet-traction, braking, and heat-shed than ever before.
By contrast, 25 years ago, a tire for my motorcycle cost about $20 and I could expect it to last 8000-10,000 miles. Failures were common and there was no warranty coverage beyond the first install. The tire maker would provide instructions and materials on the safest and permanent way to repair a simple puncture.
Today, a tire for my motorcycle costs just over $200 and I can only expect it to last 8000-10,000 miles. The price is 10 times higher and I can expect no additional miles. Failures are frequent and there is no warranty coverage beyond that it will hold air when you first install it. The manufacturers will look you in the eye and inform you that there is no-way, no-how that a single puncture can be repaired-throw the tire away. Although there have been technology improvements in the super-gummy race-bike tires, the cruiser tires perform about the same as they did when I started riding.
My point here is that motorcycle tires for my street bike are 25-year old technology, at prices we should not see for another 50 years when compared to car tires. They've got us, and they know it. Why develop new or keep prices competitive, when folks will (must) by the crap you were putting on the street 25 years ago? Simply, we are a niche market. A manafacturer will sell more car tires in a day, than motorcycle tires in a lifetime. Their R&D money goes to the car tire market. The meager development done in the motorcycle world is concentrated on the race circuit, where the publicity really is. Those tires are doing truely amazing things, but are not suitable for the street.
Tires developed for the high-performance, low-profile street cars of today, particularly for the custom/performance sect have the sizes and characteristics (and quality) that make them a possibility for this project.
Over the years I have experienced every kind of failure imaginable on motorcycle tires. Defective beads, bubbling, blistering, cracking, tread/carcass separation, radical balance deficiencies, out of round, wobble, and just the outright failure to actually hold air have found their way onto my machines. Just for the Valkyrie alone I have personally seen failures in the three top brands available to us (there are few other choices). By contrast, I have not had a single tire defect on any of my cars in the same period (and as many miles). This also includes trucks and their tires, which I abuse with reckless abandon.
Another gotcha is the horrendous inconsistency in quality, even in a known brand. I won't mention any here, but just because one size tire in your favorite brand causes no problems, doesn't mean a different size tire of the same brand will be similar in quality. When I change machines, I have to start testing tires for one I like (and that won't rapidly kill me) all over again. Even in the same brand and size, batches vary considerably in quality. I had one recent tire that needed 6-1/4 ounces of weight to balance it!
I take extensive trips, sometimes putting 10,000 miles or more on in a month, and it is expensive and difficult to get tires installed in the middle of the trip.
How many of you went through $1000+ worth of motorcycle tires last year? (Gad!)
How did you come up with this idea?
I did not. It's not my idea. Motorcyclists have been customizing their machines since the very first guy looked at a wheel and said, "Wonder what happens if I strap an engine on it?" Others before me tried this out, and so I had an idea and input of what sizes would be appropriate for my machine. Also note, several machines already have used car-tires, including several early models of V-8 bikes and quite a few custom jobs. I am not alone out here.
Many folks have selected "different from stock" tires for their Valkyrie. Some want the fat rear tires, some don't like the OEM brand, some use smaller tires and even modify their shocks and forks (to lower the Valkyrie for a shorter inseam). Any and all of these change handling characteristics.
What will your insurance company think?
If I were to ask them, my insurance company would say that riding motorcycles is inherently dangerous and not worth the risk. Don't do it at all. There are easier and cheaper ways to arrive at your destination. Nuff said?
What does the bike manufacturer think?
If I were to ask them, they would say never to work on my own machine, only use OEM parts and tires, never, under any circumstances modify anything, and for heaven's sake only have them do any work needed. They of course, would also say that they are not liable for any work they do or parts they provide, and probably if I pressed them they would say that riding motorcycles is inherently dangerous and not worth the risk. Don't do it at all.
It is interesting to note that the only officially sanctioned tire for my motorcycle (the specific brand and model listed as the only "approved" tire in the manual) is no longer made or available. The OEM tire manufacturer lists a replacement model (which IS an improvement on the original) but the machine's manufacturer does not.
Does it fit?
For the Valkyrie, a 205/60/16 provides nearly identical circumference to the original rear tire. When I first tried the car-tire there are not many tires (especially speed rated ones) made in that size however. A 205/55/16 fit fine, but due to its slightly smaller circumference, will increase your rpm at a given cruise speed slightly. My calculations say 300rpm at 80mph, but I have not bothered to verify that. Suffice it to say I did not notice any difference when I installed the tire. My most current tire is a 205/60/16 and I am really pleased with it. There are literally dozens of choices in that size now.
Some riders have installed a 205/65/16 on the Valkyrie also. This should slightly reduce the cruise rpm over stock. (shrugs).
The 205/55/16 installs with no modifications. The other two require that the fender bolt retainer cages be removed from the fender. Not a big deal. See how here
The Valkyrie speedometer reads the front wheel so no matter which one used, the accuracy will not be affected.
Did it affect your fuel mileage?
No. My mileage is the same as it was in any given condition before the change.
How does it handle?
I am happy with it. It is very smooth and stable at high speeds, and for me at least, at very low speeds (full deflection turns for instance) it is an improvement over the motorcycle tire. Basically, I've found it to be superior in all conditions.
There are two areas of difference in feel:
It requires active counter-steering to put the bike in a corner. The Valkyrie has always required a firm hand, and this is not significantly different. The difference is that on the motorcycle tire, once the bike was stable in a corner, driver input on the handlebars is not really needed. The bike will stay in the turn unless power is applied or removed, or the terrain/surface of the road changes. With the car tire, the counter-steering input is required the entire time the bike is in the corner. If it is released, the bike will straighten up on its own. Those of you that push the twisties and know how to drag pegs (really know how to turn) will understand it right away.
The other difference is in what I'll call "bump steer" Varying terrain, such as a ridge on the road, a track in a dirt road, or an angle or crown to the road will give much more feedback than they do on a motorcycle tire. The bike will have the tendency to turn downhill. At highway speeds this is not an issue (not felt), at lower speeds, again, it requires a firm hand on the handlebars and the bike remains well behaved. It is just telling you what it feels on the road. You feel the steering inputs, you do not have to accept them. I prefer the feel, as it puts me much more in touch with what's going on with the road conditions.
The bike turns as aggressively as it ever did. This has not impacted my speeds or angles of lean in turns. I can still drag pegs when I want to, and it has not slowed me down a bit. I am much more confident in wet conditions and with hard braking.
What about grooved pavement?
I found it to be an improvement, although the Valkyrie has always been well behaved. Grooved pavement does not bother me a bit with this tire. Neither do ridges or other pavement irregularities. My friend (on his XS1100) and I got into some of the worst grooved pavement I have seen just a few days after installing my first one. He was very uncomfortable, getting tossed around quite a bit. The Valkyrie did not care. I could feel it, but went straight and comfortable down the road. I also traveled many iron-grate bridges on my Alaska trip and was very confident and comfortable.
What about dirt/gravel roads?
The bump steer comes into play, but overall the bike is stable and well behaved. I found that my speeds went way up on the same roads after I installed the car tire. On gravel/dirt the bike gets more stable at higher speed with the car tire, whereas with the motorcycle tire it seemed to get less stable the higher the speed. Note that I have always been comfortable on gravel/dirt roads, even on the Valkyrie. Alaska was the real test, I traveled hundreds of miles on gravel, sand, and mud. The Valkyrie ate it all up and begged for more. It was not unusual to find me doing in excess of 70mph on open stretches of the roads. Look here.
You're gonna die a flaming death. You can't drive on the sidewall!
Hmmm . . . you're right, I can't drive on the sidewall. I'll keep you posted on the flaming death thing. No matter how far I lean the Valkyrie, I am never on the sidewall of this tire. It has molded in markings and the "rubber tits" from the mold process on the sidewall, and they remain pristine, untouched condition despite some very aggressive turning. I also set the bike over on its crash-bar one day to see where it rode, and it is not on the sidewall. All remains on the tread, and there is plenty of it. The contact patch of the car tire flattens on the bottom (as it is designed to do) keeping more half the tread on the pavement, even in full out, peg-dragging turns. The contact patch for the car-tire exceeds the size of the contact patch on the the only MC tire I had measured on this bike (Avon). An easy and fun way to measure is to find a street where water is running down it, that is otherwise dry (somebody watering the pavement again, a common thing here in Texas--I think they want it to grow). Ride the bike through the water and then into immediate peg-dragging turns. Then go look at the tracks. You'll be surprised.
How about braking?
I have much more stopping power with the rear than before. As always, your fronts are your primary, but the back helps substantially. I would guess that I could out-brake most other Valkyries, and it should be noted that the Valkyrie, as compared with the rest of the cruisers, has outstanding brakes to begin with.
It's flat! How can it turn?
Well, it's not really flat. This tire has a profile; it is just not as radical as the motorcycle tire. Remember that it is the back tire's job to stabilize the bike, in turning it is the front tire's job to de-stabilize the machine so it can lean into the turn. With the different profile, this back tire is just trying a bit harder to stabilize me. It does not reduce my turning response or authority. My line and speed into hard corners is unchanged, and I have the added benefit that I can absolutely slam the throttle exiting the curve without so much a squiggle. The Valkyrie on the stock tires or the Avon rear would spin it out from under you, resulting in all sorts of unpleasentness. One more advantage is that "flip-over"...that is, coming out of a hard turn in one direction to a hard turn in another direction is substantially easier and faster than on a standard tire.
It'll blow off the rim. The beads are different. Fiery death thing again.
Untrue, the beads are the same. This tire is designed for this type of bead (the Valk rim/bead is identical to the rim/bead on the aluminum wheels on the wife's car. In addition, the tire's specs approve it for this width of rim (the Valkyrie rim is 16x5). As long as there is air in it, this tire isn't coming off. Indeed, on one occasion, I got three big screws in the rear car-tire. I felt it, and decided I could get it home. It had 5psi in it and was still rideable, although I wouldn't want to try dragging pegs with pressure that low.
Are you going to put one on the front?
No. The front tire's job is profile dependant. It could be done, but substantial modification to the rake and angle of the steering head would be needed.
If you ruined this one today, would you put on another car tire?
Yes . . . I am now on my third car-tire. I will not be going back to a mc tire on the back of this machine. I still have two Avon Venom R rear tires in the garage that I removed due to getting a flat (nails). I was out of "stinger" patches at the time, so I had to replace them. Between the two of them, there is probably 15,000 miles left to run. I'm not going to bother with them. They have been permanently repaired (stinger patches) and sit in my garage in case a friend or rider in our local group needs a tire fast (edit, I finally gave them away).
What did you look for in a car tire?
I looked for a symmetric, directional tread pattern, with solid, beefy chunks of tread near the outer edges to minimize squirm. I liked the solid tread in the very center of the tires I've selected. . . this is a feature that helps make tires quiet, and it has helped. This tire is noticeably quieter than the motorcycle tire. I also looked for a high speed rating. In specific, the first tire I selected is the Yokohoma ES-100 series. 205/55/16, "Z" rated. I wore it out in the Yukon Territories and installed what they had (a Nokia 205/55/16). When I used that one up, and in preparation for my Route 66 run, I installed a Goodyear Assurance Triple Tread, 205/60/16. I'm quite happy with it. In my experience, "profile" and sidewall stiffness are pretty much irrelevant. I'll probably try the Toyo Proxis next (shrugs), not really sure.
How long did it take you to get used to it?
I had the feel of it before I hit the end of the alley (1/4 mile?). I drove 3 blocks up to the nearby grocery store's parking lot and did a bunch of slow speed stuff. It was surprisingly easy. Figure eights, full deflection turns, emergency braking. All very nice. I was confident inside 10 blocks.
After about 200 miles I did not even notice the difference anymore. It is very much like getting off your machine . . . the one you have ridden for thousands of miles, and getting on a different brand or size of bike. It handles differently. Not worse, not better, just differently. You can handle it, and in a short time, you won't feel the difference.
What about front tire wear when you're running a car-tire? Better or worse?
The same as far as I can tell. I run an Avon on the front, and got 21,000 miles out of it, including the Alaska trip. That's pretty good for me.
Are you going to do more testing? What's next?
I've run these tires in all conditions, and in all speeds. I took my machine to Alaska and confidently rode in an amazing variety of extreme conditions, including mud, snow, sleet, sand, and gravel. I also rode twisties galore, super-slabs, and general putting about town. I've found no circumstances where the car-tire is a disadvantage.
Can I try yours to see if I like it?
Usually not. It is a rare few that I let ride my machine . . . and I think if somebody just rode this a block and came back, they would be left with an incomplete impression. It really takes a few miles to get used to it.
Is it right for me?
Well, if you have to ask me, then the answer is no. It's your machine, your skills, confidence, and comfort level. I do not find it limiting, unstable, or dangerous, despite some extreme riding under varying conditions, and intentionally pushing the envelope in more controlled areas.
What about cost?
Cost is not my real motivator, but it is an advantage. I paid about $95 for the tire, and paid $20 to mount it. I can mount them myself now, as I bought all the stuff to do it, it just had not all come in yet. The last Avon I bought cost over $269 w/tax (cheaper on the internet) and cost the same $20 to mount. Others that are running car tires are reporting 20,000 and 30,000 and even more miles out of them (note, on the Valkyrie you still need to remove the rear wheel and lube the splines every 10,000 or so).
I'll spank you with my GX'er
Okay, I get this one a lot. Not to put too fine a point on it, but aside from the rather bizarre sexual implications of that statement, you most certianly won't....at least not if I get to choose the course. Please note, the Valkyrie is a Heavy Cruiser, or what might be called a Power Cruiser. Loaded, it weighs over half a ton. Nothing I can do to this machine will make it outhandle a gummy-tired, 400-pound crotch-rocket in the corners. When I'm throwing sparks off the hard-parts and hanging off the side of the bike, that is the maximum cornering I can get, regardless of tire. What this means is that the Valkyrie is not made to spank your GX'er in the short term. It's made to cruise. That's what I bought it for, that's what I use it for. It corners remarkably well among the heavy cruisers, but it's still a heavy cruiser. Oh, my choice of course? Well, it has lot's of nice cornering roads...but it's 10,000 miles long and involves more than a dozen states, two countries, and a couple or three Canadian Provinces. There's several hundred miles of gravel involved too. Just how many tires can you carry on that GX'er, how deep is your pocketbook, and how fast can you change them on the road?
I've read what you said, but there is just no way it could work.
Well thanks for so casually dismissing my 30-odd-years experience on motorcycles. Seriously though, I've put over 100,000 miles on car tires just on this bike. I've ridden many of the most challenging motorcycling roads North America has to offer. I've sacrificed enough chrome and thrown enough sparks to the road gods to go through several sets of riders pegs and crash guards. I consistently take this machine places where people tell me a cruiser has no business going. I've no real interest in debating whether it works or not. HOW it works is an interesting question. Whether it works is an irrational discussion at this point.
I'm still not convinced it's safe.
It's not my job, intent, or duty to convince you of anything...especially the safety of motorcycle riding. But consider this: I ride, and ride hard. In the first 16,000 miles I had shredded 5 different motorcycle tires off the back of this machine...FIVE times I had to get this machine to a stop from high speed with a flat, shredded, or unseated tire and limited handling capability. These were not cheap or off-brand tires! Since I switched the rear to the Darkside, that's 100,000 miles now, I've had two rear flats...and both of those were ridable to get it home and/or the tire store to get it patched. Neither unseated or caused me any handling difficulty...it just felt wierd enough to get my attention. So, define safe?
I hope this has answered some questions, and I will add any more as they come in.
Some more pictures and explanations follow:
Based on other's experience, I expected to make 20,000 miles out of my first car-tire. I actually only made about 13,000, although it could have gone further. By the time I reached the start of the Alaskan highway, I already had traveled 5000 miles to get there. In addition, I aleady had 5000 miles on the rear tire before I left. I was running the pressure at 44psi and that turned out to be a little high and that, combined with the harsh conditions (that gravel up there just EATS tires) wore the tire more rapidly in the center tread then I would have liked. On my return over "the top of the world" I decided that since I was still 6000 miles from home, and had several interesting roads lined out in front of me, that I would go ahead and replace the rear tire. I showed up at the tire place before they opened, pulled the wheel, and presented it to them when they showed up for work. They had a Nokia 205/55/16 and I pointed at it and said, "Put that on there." I reduced the pressure I was running to 34 and I got 22,000 miles out of that tire.
Replacing my tire in Fort Nelson, British Columbia. 13,000 miles and the gravel roads had taken their toll.
Prepping for my summer 2005 Route 66 run I decided that 23,000 miles was enough and I'd go ahead and change out the Nokia tire. I could have gotten more miles out of it, but had a long way to run and decided I didn't want to mess with it in the middle of my summer trips. It was time to pull the rear-end apart for spline/driveshaft service anyway, so I went ahead and changed the tire.
Pulling the Nokia, preparing for more long trips. This tire has over 23,000 miles on it.
Critics of the car-tire concept usually start out with talking about how the sidewall is not made for driving on. In that, they are correct. Sidewalls aren't made for driving on. The good news is, that I don't drive on them. I've adressed this and contact patch both in the text above, but here is some proof for those still skeptical...The pic below is of the Nokia tire I pulled off after 23,000 miles. Much of that was in very challenging conditions. Note that there is no wear on the sidewall. The little mold "tits" are still there. Also note that the tire is wearing more in the center than the edges. The reason for this is that even in extreme cornering, the center still is on the ground...with 3/4'ths or so of the tread always in contact. This results in more center wear despite pressures run. Higher pressures will make this worse, and do not improve the handling.
Note, NO wear on the sidewalls despite 23,000 + miles of...ur...enthusiastic abuse.
Note the wear in the center...I could have gotten a lot more miles out of this tire, but had several summer trips lined up in a row. Change now, or in the middle of a trip. I chose now.
My new Goodyear Assurance Triple Tread...205/60/16
One of my VRCC friends posted this and I just couldn't resist.
And finally...a snippet from a recent email exchange...
Him: "You know you're a test pilot don't you?"
Me: "Yes. Yes I do."
Him: "That doesn't bother you?"
Me: "No, not at all. I've got news for you. I LIKE being a test pilot."
Him: "But...anything could happen."
Me: "Actually, I'm counting on that. It's why I ride."
Anything could happen.
I'll see you on the road...