tire pressures

[emiel]

what tire pressures are you guys running.I have BF goodrich competition t/a on my car.In the build manual of gtd they propose 21 and 23 psi but this sounds so low.I have run between 28 and 30 psi but the rear tires are wearing out in the middle so this clearly is too much.Any advise.

[Gary Kadrmas]

emil,

When tires wear out in the center, it usually has to do with too high of tire pressure, or the combination of too narrow of a rim for the tire, or too wide to a tire for the rim. You might share us with your tires sizes and rim widths. And....are you referencing both the front and rears, or just the rears?

[Malcolm]

I ran the GTD recommended pressures on those tyres and it worked well enough for street use. Wear in the centre would indicate to me also that pressure is too high. On track you need to find your own set up preference but wear rate will likely increase when you get the best performance! Just be warned those tyres are not good on track and quickly become very greasy in feel!

I have a set of slightly (but evenly) worn rear tyres sitting in my garage if you are interested? Perhaps 7 or 8 mm of tread left? They are 265/50/15 with the V speed rating.

[emiel]

On the rear I'm running 265/50-15 on 9" rims and in the front 225/60-15 on 7" rims.I'm now also running on the gtd pressures for a year and it seems ok.I know for the track they are not that good so I want to buy Avons and wider rims for track time.Malcolm you have a pm.thanks guys Emiel

[Howard Jones]

My advice is if you are thinking about a second set of wheels for track use, you should at least consider 17" wheels. The number of tires avaiable in 17" is too long to list. Many can be bought for 1/2 the cost of equal peformance 15" tires per set.

The look of 15" or 17" wheels is what it is, but if you intend to run on track then I think that performance bang for your buck is much greater with 17 inch wheels. Some of the Z rated summer only max performance tires are really very good trackday tires.

I run my 17" 245.40.17 F and 315.35.17 R at 26psi F and 27psi R as a starting point pressure. I usually see at least 3-5 psi increase on a warm day. warm = 80F - 90F air temp
and have seen 6-7 psi increase on hot day +90F AT.

Oh and I agree on the 15" BFG's. Be very careful with these on track. They will really get slick (read no grip) when they get hot. On a hot day they go off in about three laps. Just about the time it takes for you to feel good about going for it.

[Mark Paris]

Malcolm,
You have a p.m.

Regards,
Mark

[emiel]

thank you Howard for the advise.Pure out of performance youre right with 17" wheels but I like so much the sixties look with 15" rims and the fat rubber.I choose for the Avons 295 in the back and 215 in front.Now just waiting for the next track day.