New Hoosier R7/A7

[DocWyte]

33-33psi hot Terry? Not 38-40?

[NotoriousJJE]

I found 41 hot to be faster than 38. Tried to run it in the low 30's like some suggested here once but the sidewall deflection was so much, I blew a tire going around the hairpin at Sebring. Won't do that again. This is on 245/40r17's on 17x8 wheels (maximum STU width). Car weighing 3100 or so with me in it.

[TXBDan]

The Hoosier A7/R7 tire care guidelines are interesting:
http://www.hoosiertire.com/images/co...s/TCTR7_A7.pdf

It emphasizes the initial heat cycle procedure that alwaysinboost mentioned. It also shows a recommended hot pressure of 40-42PSI on a 3000+lb car.

[Jfriday11]

I've always done Hoosiers recommended break in procedure and never have had any problems with the tire suddenly falling off. Usually get 16 heat cycles out of the R7's before times start dropping a bit, but then again I was running 15min TT sessions so maybe longer sprint races are harder on them. Also I was running 36psi hot at 3100lbs for the majority of the season until I spoke to Hoosier at nats and followed their psi recommendation at 40psi. It significantly improved my times.

[DocWyte]

I've always run 39-40 psi hot, car weighs 3200lbs with me in it, TTC prepped.

[John in Houston]

That's too hot for the R7.

[DocWyte]

What do you run John?

[John in Houston]

28/26 cold

[alwaysinboost]

I found 41 hot to be faster than 38. Tried to run it in the low 30's like some suggested here once but the sidewall deflection was so much, I blew a tire going around the hairpin at Sebring. Won't do that again. This is on 245/40r17's on 17x8 wheels (maximum STU width). Car weighing 3100 or so with me in it.

245 on an 8" wheel is WAY too narrow of a wheel, no wonder you had a blow out. YMMV, I run 225 on either 8.5 or 9" (preferred) and have gone down as low as 30psi HOT with no issues.

[NotoriousJJE]

245 on an 8" wheel is WAY too narrow of a wheel, no wonder you had a blow out. YMMV, I run 225 on either 8.5 or 9" (preferred) and have gone down as low as 30psi HOT with no issues.

Certainly not ideal, But maximizing tire width per the rules my man. I think it is a fairly common setup for the STU guys.

Ran a 225/50r16 on a 16x7 wheel for years in ITS. Definitely not ideal, but limited in rim width and maximizing tire width...

[CoMZ302]

Certainly not ideal, But maximizing tire width per the rules my man. I think it is a fairly common setup for the STU guys.

Ran a 225/50r16 on a 16x7 wheel for years in ITS. Definitely not ideal, but limited in rim width and maximizing tire width...

Yeah, when the class you chose limits wheel width, pretty much everyone tries to squeeze on as much tire as they can.

The E Production SCCA guys are running a (really wide) 245 slick on a 7" rim. It looks ridiculously stupid - and is winning all over the country. Many people have tried the 215s on 7s (myself included) and they are faster for a lap or two, but the braking isn't nearly as good and they get overheated pretty quickly.

It's racing man; stuff that works on the boulevard generally doesn't work on the track, and vice versa. Heck - really fast autox stuff usually doesn't work on the track either.

[JS154]

245 on an 8" wheel is WAY too narrow of a wheel, no wonder you had a blow out. YMMV, I run 225 on either 8.5 or 9" (preferred) and have gone down as low as 30psi HOT with no issues.

YES I KNOW this is an old thread, but when i saw this comment I couldnt resist calling it out.

imma call TOTAL BS on that. 245 on an 8" rim is just fine, plenty of people running that combo for years without any issues or odd wear.

That is most certainly not the reason the tire blew out.


the only person on the SCCA rules committee pushing that false agenda was a guy with an illegal car that tried to get the rules changed so his car would be legal. When that was told to Hoosier (245 too wide for 8" rim) they LITERALLY laughed at it.

you went down to 30 psi HOT. THAT is your problem. along with your lack of setup knowledge.

FACT

[ScotcH]

you went down to 30 psi HOT. THAT is your problem. along with your lack of setup knowledge.

FACT

I don't know anything about his setup and lack of knowledge, but running 30 psi hot is not that bad. Probably a tad low, but we used to run 32 psi hot all the time, and sometimes dipped lower. It's the cold psi that can ruin a tire ... for sure true on soft sidewall tires like the pirelli. The Hoosier/Contri slicks are like bricks ... super stiff sidewalls.

Now granted, we ran 245 on a 9", and only 2750 lbs