Topic: Squared tire

[Kevin D]

 This BT45 has about 4500 miles on it. I knew it was going to happen. There are too many straight roads around here and not enough twisties. Good tread left in the center but its a little unsteady when I do manage to get out on the edge.
 
 I found some discussion elsewhere regarding "shaving" car tires for racing use. I saw a $7200 machine spin a car tire into a knife edge, a tire lathe. I have an idea that this BT45 would perform like new if the edges were knocked down a bit, more like the original profile.
 
Anybody ever done anything like this? I am thinking a belt sander will do the job.

[eurban]

Personally I'm not sure that messing with the tire is worth the risk and money saved.  But if you do try to reshape make sure that you do a consistent job all the way around.  You may find that any uneveness will surprise you when you lean over.   I don't think you will be able to achieve this with a loose wheel and a hand held belt sander.  Perhaps if you leave the tire mounted and hold the sander on the swing arm you can spin the wheel and sand more evenly?  Have fun . . . .

[Tretnine]

I think eurban's got it. You've got the right idea, and I've actually been thinking about this lately (I could get another season out of my front if I could get it shaved.) Anyway, the difference is the tools if the machine costs 10k, I'm not sure how you're going to replicate the precision with a belt sander, it doesn't take much to get a tire out of balance or to make you feel uncomfortable riding.

Maybe there are places that actually do this. I know that there are places that will shave tires for 4 wheel drive cars because all the tires on those need to be the same size. That way, when you blow one tire you can get one shaved instead of buying a new balanced set of four. Makes sense that somewhere is doing it for bikes.

[andy750]

What size is the tire? It looks much wider than stock...is it?

[nvr2old]

Belt-sanding a tire sounds really dangerous to me. Seems like a lot of work just to save a few bucks. You want an even contact patch at all times. Get a new tire. They're cheap compared to the danger you're likely to bring to yourself on an altered one.

[TwoTired]

Looks like typical wear issues from putting oversize tires on narrow rims.

Are you running higher than spec air pressures, too?

[Kevin D]

Thank you all for your concern for my health.

The tire is a 120/90-18, maybe one size up from stock, and its about $120. I run 30psi riding alone and raise that to 35 when I double up. I think the tire is good for 40+psi or so.

I've never done this job before, I'm asking if anybody else has and what the right tools and methods might be.

10000 miles is my goal/standard for a rear tire and if I have to pitch it at 4500, well, not the best. There's enough center tread left that I might make that goal. It's not the first tire I've squared, I just never had anywhere like this terrific sohc4 resource to ask about it before.

Heres somebody elses 5000 mile, pitched, example:

[andy750]

I had the same problem on my 750 Kevin:




The tire on the bike is a BT-45 120 whereas the one being held up is a 110. I switched back to a 110 size following Llyods comments (see above and long time ago as well). My tire was so square that riding corners became dangerous for me -and I dont take corners easy either ;-).

Currently with the 110 BT45 I have 6000+ miles and still looking good. And thats been a mix of 1 and 2-up riding. I run 34+ psi - I find 30psi too low for both back and front. Both tires are rated to 40 psi. Low psi on the front gives me a 35-40 mph speed wobble.

cheers
Andy

[TwoTired]

When you remove the rear tire, measure the rim internal bead width.

Any tire you put on there has a manufacturer spec for fitment onto a rim size.  It may not be easy to find, mind you.  But, there is one.
The 550 rear wheels are 1.85 inches in width.  And, a 120 on that size rim pinches the bead together and makes the tire crown more than it was designed to crown.  This accelerates wear at the center of the tread.
Anyway, a 120 tire on a 1.85 inch rim is at least two sizes oversize.  The 120 tire I put on my 550 wore out in the exact same fashion yours show wear.

I went back to a 4.00 rear tire on the 550 and it wears pretty evenly now.

[Kevin D]

Heres from Classic in Holland:

RIM REAR WHEEL
Did wheel rim 2.15 x 18 Inch 40 Holes, new production by DID/Honda

And heres from Bridgestone:

120/90-18 Approved Rim rear(2.75)2.50-3.00

So yes, the tire is over one(?) size.

FWIW the second pic was from a stock sized 5000 mi bt45 on a BMW.
http://www.webbikeworld.com/Motorcycle-tires/metzeler-lasertec/