BFGoodrich g-Force Car Tire on a Rocket III Motorcycle


My buddies keep saying things like this:

“That isn’t a motorcycle tire. That’s a car tire. Motorcycle tires have to be rounded over on the shoulders so you have maximum contact patch when cornering. You won’t find a tire shop or motorcycle dealer that will be willing to mount that thing on your motorcycle wheel, no matter what you pay them.”

Okay, I’ll mount it myself if I have to.

Even if I have to buy my own tire changing machine.

A home shop tire changing machine will cost around $1,000.00. The 225/55ZR -16 BFGoodrich g-Force T/A KDW 2 I just purchased from TireRack.com is $160.00, shipped.

A new Metzeler rear tire for my bike costs around $320.00. Another $100.00 plus for mounting. And they wear out in less than six months.

A car tire will last about three years.

Do the math.

Now, as for the danger, I really can’t find any. It’ll get better traction on the straight roads, and the contact patch looks to be pretty much the same on the corners with this tire as it would be on the straight-aways with the Metzeler. But on the straight-aways with the car tire I’ll have about 300% more contact patch.

Here’s what I think: I think the motorcycle tire manufacturers and motorcycle tire shops have a sweet deal going by creating a psychological monopoly. Sticky, soft compound racing tires are great for racing, but they aren’t great for routine commuting. They wear out fast, causing folks to run on thinner tread more often. They may stick well in the curves on clean, dry pavement, just like racing slicks get better traction on the drag track, but they are far less worthy of traversing wet, dirty, or loose substrates than a car tire, whether the bad road conditions exist on straght-aways or curves.

As the youngsters say these days, "This is going to look sick!"
I’ve read through hundreds of forum entries and articles, and the only people I see who are dead set against using a car tire on the rear of a Triumph Rocket III are the ones who have never tried it.

The ones who have tried it? I’ve seen about 200 so far, and only four of those have gone back to motorcycle tires…not because they think the car tire is dangerous, but because they preferred the feel of the traditional motorcycle tire.

And I can find no (zero, nil, nada) first hand reports of accidents attributed to running car tires or as a major contributing factor.

I may be 100% wrong, but I’m going to try it. Installation happens this Saturday with the help of my genius mechanically inclined and experienced younger brother. He’s one of the skeptics, but he’s also familiar enough with me to know I’m gonna do it anyway, so he may as well make sure it’s done as right as it can be considering we’re mating the worlds of motorcycle and car technology with live testing in the production environment of real world traffic and highways.

If I’m still posting articles next week you’ll know it didn’t kill me yet.

I’ll do my best to stay un-biased and tell the truth if it sucks. I don’t mind admitting when I’m wrong. Right now I just don’t see any down-side to this and can’t trust the nay-sayers who can’t come up with any mathmatical or legal reasons why this shouldn’t be done.

If it was so dangerous and risky why wouldn’t it be illegal, void my warranty, and be listed all over the place as something that would negate insurance coverage? And why wouldn’t there be actual news media and motorcycle magazine stories about the crashes and resulting casualties?

All I’ve seen are a few anecdotal horror stories in forums posted by some anonymously monikered member whose brother-in-law or best friend wrecked out on a car tire while doing five miles per hour in a school zone and subsequently hastened the apocalypse and started having naked babies.

avatar Motorcycledave

Deals Gap 22 times lift the front tire out of every corner on a 205,60,16 Potenza, cross country and back three times dragging a trailer twice, Bear tooth pass and the Harley guys said how did you get there and back so fast, I told them it’s a sports car tire.
The Dark side is all about ecconomics, fun tooo.

avatar gary copeland

I have about 1,500 miles on a 235 on the rear of my rocket. You have to muscle it more in curves, but get use to it. My first metzler only lasted 6,000 miles, number two 3,000 miles. Both tires were separating and metzler would not do anything about it. The metzler was about $340 and the 235 was $135. I do not plan to ever buy another metzler.

avatar mike

my buddy is fighting for his life quite possibly because of this so called great idea. his triumph went into a speed wable and left him a terrible broken mess 8hr. back surgery yesterday every complication and broken bone you ca imagine for crying out loud save money by drinking afew less beer or taxes or smokes or your damn iphone.

avatar Hal Bjorkman

I have a Federal 255x50x16 on my rocket and I love it. it is rated at 149 mph just like the Metzler. I have had it to 160mph. I have put on about 2000 miles and it still looks new. It was 130 dollars at Les Schwab tires. I put it on myself (not recommended by hand). The tire is 10.5 inches wide and fits fine. I have yet to brake traction starting or stopping. I feel a lot safer. Now the bike stops as fast as it goes. Darksider. you can see pics at facebook Triumph rocket iii group/ Robert Bjorkman.

avatar norm

I got tired of replacing big expensive Metzelers so resorted to a car tire. It has already outlasted two Metz and looks hardly warn. The local triumph dealer told me that it was a horrible idea but he sells Metzeler tires. When I want to road race, I ride my Bonneville.

avatar Brandt

I don’t know much about motorcycle tires. I’ve never seen a square tire on a bike, or heard stories about it. I have, though, seen a car pop up on a concrete median and rip the wall of a low-side tire out when it dug into the pavement. My only concern is that car tires aren’t structurally designed to make that kind of contact for extended periods of time. Furthermore, if the shoulders are square, wouldn’t it shift the bike’s, and by extension, your center of mass in a non-centrifugal way (up, for instance) when you leaned over it? Maybe it’d be insignificant, but I think it does change the physics of a turn.
If you’re finding enough success stories out there, though, have fun. It definitely seems economical.

avatar mike

I had a car tire for a short while on my valkyrie. had it about 4 months and while my biggest worry was handling in corners I have to say I had no issues with cornering. finally gave up looking for that “weak spot”. what turned me off was how it was initially harder to turn into corners and have it all of a sudden get easy as you lean far enough into a corner and hit the tire “edge” and on certain sweeping corners where you are holding a certain lean angle that is on the edge you have to perform a balancing act as it will want to go one way or the other. 100% attention is required in corners. great for straight hiways thou. nothing better.

avatar Greybeard

“Back in the day” I put a square-shouldered tire on my Kaw 750 triple because tire wear was costing me a fortune. That bike was no canyon carver anyway… it was good only for going very fast while sounding like a swarm of hornets going straight for about a quarter mile or so. Cornering with that tire gave me all the grip I really wanted… I’ve known forever that my last name is not Agostini.
Do it. Then just be careful stuffing the thing into the apex.

avatar D Murray

The cost and durability numbers are great. Suppose you took your rear wheel to the dealer and told them that this was for your sidecar equipped motorcycle. I’ve seen BMW K1200 LT’s with three car tires on sidecar rigs. Good luck!

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