wneils

So the track old guy said the Z-51 runflats should scrub out to these arrows on the sidewalls after a run. If they don't reach them you have too much pressure.

At 27 lbs all around I am still a little short.

Any truth to this. Thanks

Bill Dearborn

You could drop the pressure to 0 and get about the same rollover. Performance with run flats is not about getting max rollover but keeping all of the tread on the ground.

I don't know about the newer design runflats but my experience with the original C5 run flats was that you had to increase pressure to get the best performance out of them. I had 3 sets of those tires in 3 years and all the front tires had unusual tread wear when I autocrossed or went to Watkins Glen. The wear was offset from the center of the tire about an inch and a half toward the outside. It looked like a groove around the tire. I found that by running those tires at 35 lbs cold pressure I could reduce the amount of wear.

I am not sure what was causing the problem but I suspect it may have been due to the very stiff sidewalls of those tires. My belief was the tire tread was buckling under severe cornering forces (max rollover) and actually lifting off the ground in some places which put more force on the part that was still in touch with the ground. The higher pressure reduced the buckling, kept more tread on the ground thus reducing wear and improving cornering force.

Bill

wneils

Makes sense.

Bill

fhturner

Perhaps you already know this, but these aren't actually "tire scrub arrows"...they point you to where the treadwear indicator bars are on the surface of the tire.

davidfarmer

I consider those "danger zone" markers personally. With a proper track alignment, the only real way to determine pressures is by measuring tire temps. Find someone with a probe pyrometer (memory is best) to read temps for you.

Aardwolf

That is correct. I have had guys tell me about the triangle wear markers at the track before though too, to bad it doesn't work like that.

gkmccready

Those little triangles are just telling you where the wear bars are for judging remaining tread depth.

The shoe polish on the sidewall trick obviously doesn't work for runflats, either.

As I think David mentioned, tire temps are the way to go. And for the fellow that liked a 35psi starting pressure... when I ran the runflats they got real greasy when the temps/pressures got up... they seemed to work better with a 28/26 starting pressure for me.