jaydubya

Anyone have suggestions? I started off with the same hot pressures that I use for the Hoosier R6, and those numbers are consistent with the (large) range that Tire Rack suggests, but perhaps I'm off a bit.

I went out on a set of Hoosier R6s with about 15 heat cycles this past weekend and replaced them in the next session with a new set of Kumho V710s. Sizes were slightly different:

Hoosier
224-45-17 front
245-50-17 rear

Kumho
225-50-16 front
265-45-16 rear

I ran 36 psi front and 34 psi rear hot in both tires. The Kumho V710s were noticably slower with less grip than the Hoosier R6s. Also turn-in was not as sharp with the V710s and they were generally less communicative.

Camber is -2.5 front -3 rear.

Cheers,

Jeff

Joe Weinstein

I have found that kumhos want significantly less pressure
than Hoosiers. Your pressures do sound about right though,
unless your car is very light, in which case I'd try lower.

jaydubya

Thanks for your response Joe.

My car is 2450 lbs with 1/4 tank, 2670 lbs with me in it.

Should I try lower than 34/36 hot?

Curious if you have any firsthand experience with comparing the V710 to R6... should I expect comparable grip or is what I have experienced expected?

Cheers,

Jeff

mm86911

I ran 38 hot all fours in March and rand within .5 secs of R6s same pressures.

jaydubya

Same day?

Which were slower?

What does your car weigh?

Cheers,

Jeff

Joe Weinstein

A pyrometer should do better than our speculations...
Joe

jaydubya

Yes, I will check temp and distribution with a pyrometer next time I have them on the car.

However a data point from you would be helpful nonetheless...

What does your car weigh?

Will changes to my car setup, tire pressures and driving style for the 710s result in equivalent performance to the R6 or are the 710s just slower?

Cheers,

Jeff

mm86911

Same day within 2 hours and 5 degree ambient temp variance. Car weighs 2740 with driver and 7 gallons fuel. (PCA E stock). The Kumhos were faster but you know driving can easily vary that much. As for the R6's I find they are great out of the gate but fall off faster. The Kumhos come on slower but maintain grip longer - I would definitely use the Kumhos for enduro. Same setup for both tires and temps with 10-15F swept across each tire in hot pits.

jaydubya

Very helpful info - thanks a bunch!

Your car weight with driver is very close to mine.

Once I have some more time on them I'll post further impressions...

Bigpinekey

I've been running 710's for a couple of years and through my own experience and that of guys who run in the T1 series, the 710's like the mid 30's hot. I start out in the mid 20's (~25) cold in my Z06 and they'll get to ~34 when they peak out. I know one guy who starts the rears out in the teens, and he's a nationally ranked racer.

A tire pyrometer is the ultimate answer.