powdrhound

Gonna run R7 255/35/18 and 335/30/18 this weekend. What hot pressures do you guys shoot for? On NT01 275/35 and 335/30s I run 32/33 hot. Thinking 34/35 hot on the R7 since they have a lower load rating. Let's hear it boys...

Spyerx

Tom@TPC Racing

What's the weight of your car? On 3200 lb+ cars(specially with high power output) we run higher pressures of 38psi as per Hoosier's recommendation for durability/safety. Same for tracks will higher banking such as Daytona and Watkins Glen. On a lighter and lower power car such as a stripped out 987 Cayman we run 32/34psi or 34 square.

FJSeattle

35ish

powdrhound

Car is 3150lbs, 600hp to the wheels on Cup suspension with 1400/1500 springs. I went out this morning to scrub them in and let them sit for a day before running them for real tomorrow. Set cold pressure at 27/27 and did 6 laps slowly increasing the tempo to gradually build heat into the tires. Last lap was driven at about 90%. When I came off they were around 150F and 34/36 and still felt great. I would imagine at 10/10s I put another 2 psi into them ending up at 36/38. I think I'm gonna start them at 27/27 again tomorrow and see how they feel. Maybe shoot for 35/36 hot.

Good to hear other guys experiences especially those running the 255/335 R7 size. Funny that the 255/35 actually measures a little wider than the 275/40 R7.

Tom@TPC Racing

35/36 is gripier than 36/38. 36/38 the rears will hold up better to the power and the weight of the turbos. You'll have to evaluate your final target hot pressure base on your car's power, suspension setup, and how many HC's you intend to run a set of these tires.

Hoho has cheater sizes...

powdrhound

^^ Thanks. I'd be thrilled if I got 8 cycles on R7s. Realistically I'm thinking 5-6. On NT01s I get 12 and they're worthless at that point.

powdrhound

So I ran two sessions on the R7s over the weekend. The tires were very easy to drive with a surprisingly nice predictable breakaway similar to the NT01s. I started them a hair lower at 26.5/26.5 than the day before and ended up just slightly above my target of 35/36. My impression is that grip starts to suffer with pressure above 36. Even at the lower starting pressure I did not detect a compromise in sidewall stiffness. I think 26/26 might be the way to go for starting pressure. I did notice that they do take a little longer to come up to optimum grip compared to the 275/335 NT01s, 3rd lap seemed to be the money lap on the R7s when optimum grip was reached. The R7s also seem to gain slightly more pressure during the run compared to NT01s, about 10lbs vs. 8lbs. This makes sense as the NT01s have more thermal mass as they are 5 lbs heavier per tire and as a result will absorb more heat.

Right out of the box I ran an easy 1:53.40 at HPR (High Plains Raceway) with predicted high 1:52s on subsequent two laps on both of which I ran in traffic unfortunately. My personal best on NT01s was a 1:53.99 and considering I was still trying to feel the R7s out a bit, I was pretty satisfied. I think with more time on the R7s, mid to low 1:52s are doable which would put the R7s about 1.5-2 seconds quicker than the NT01s per 2 minute lap. I swapped to NT01s after the first two sessions and that confirmed the time gap between the two tires. I did take caution not to slide the R7s much and tire wear after two sessions seemed very low so I'm hopeful of getting two days out of these. It will be interesting to see how many sessions I can get before they start dropping off.

Over all I'm pleasantly surprised with the R7s and ordered another set. I'm curious how the A7 would compare as they would probably be better at running shorter 10-15 min time trial stints. I'm also going to try the Hoosier slicks in a 265/645 and a 320/650 to see how they compare.

AGO

My experience with the first set of R7 that I run is similar. I corded the rears after 9 HC at COTA (235 and 315's on 19's), but I think I slide them more than I should and I had a session where pressures got to 40. They were about 2.5 sec quicker than MPSC2 that I've been running. Very nice feeling, very direct and changed a bit the balance on my car with much better front grip tending to be a bit looser than with my previous setup. Maybe with more tire width you'll have better wear than I did...

Spyerx

yeah pretty much. hoho are good for ~2 secs a lap around here (2 min lap tracks) and slicks another 2 on top of that...