Toyo Tire Wear Question

[joetiii]

I put a set of Toyo R1Rs on my 69 last year. At that time I also had more camber dialed out of the car -.75 in the front and -1.5 in the rear. The fronts have 205/50 R15 on 7 inch rims and rears are 225/45 R15 on 7s as well. I figured I would check the tire wear after this driving season and see if the tires would need to be swapped on the rims. What i discovered was the fronts show almost even wear across the tire surface. In the back, I thought the outsides would be thinner tread. But I noticed that the middle of the tire is almost completely down to the wear bar and the outsides have almost as much tread as the fronts and are even side to side. I run 30 lbs rear and 28 in the front. The right rear is more worn than the left and I suspect that this is due to the power coming out of the right side open differential.

My first thought is that I am blowing up the rears too much since the middle of the tire is worn most. The second thing I'm thinking is the 8.5 inch wide 225 tire and stiff R1R sidewall is causing the middle to bow out and wear more. Could it be this tire needs a wider rim than 7" to wear evenly? or is it tire pressure related?

[racer]

I say show us a few pics. Sometimes seeing how the car is sitting on the tires can be explanation itself.

[DYB]

I have have done exactly the same thing on 2 pairs of rear R888's. I would love to know the answer. They show all the signs of being run while underinflated but like you i run around 30psi and have - 2 degrees of rear camber.

Another club member here also had exactly the same problem.

Dont know whether it is driving style or the tire ??

[Neel]

Typically, overinflation wears the centers out, uninflation wears both edges out.. Your pressures appear to be ok.. Too much/little camber would wear an individual tire on the inside/outside edge.. You may want to try an 8" wheel on the rear with your current rear tire size..

[DYB]

Not sure the wheelsize is to blame. I run 225/50 R15 on a 8 inch wheel for the R888's and have exactly the same problem.

As previously stated they are on the rear and inflated to about 30 psi cold (34 Hot).

Is suspect it maybe a toyo specific problem. Would love to know if others have had a similiar issue and found any resolution.

[racer]

My RA1's used to wear evenly across the rear.. no doubt from a combination of alignment and sliding the car around. Unsure offhand what the R1R tires look like and their make up.

Consider though that 60+ percent of the weight sits on the rear tires. Too much neg camber and the insides wear.. not enough and the outsides wear. In general, I would expect a 911 to wear the inside/middle on the rears more than any other spot on the tire.

Not easy to fit an 8" wheel on an early, unflared car, which I imagine is what the OP has.

[aston@ultrasw.c]

on a 7" rim the 225 is at the minimum recommended width

on a 7" rim the 205 is almost at the maximum recommended width (7.5")

this may account for most of your uneven wear issue

typically on a track car you want the widest rim for a given tire, or the narrowest tire for a given rim - your experience seems to support this guideline

[joetiii]

here's a photo of the rear tires

[KTL]

Doesn't look *that* bad....... Measurement with a tire tread depth gauge would give you a better idea of how bad it is. You can use the depth gauge side of a dial caliper as well.