i'm trying to choose which one of my street tire to run on the track in a few weeks.

My last time i ran with on dunlop fm 901 195/50/15 tire at 40 psi on rota slips. 2.2, 2.3, 2.5 60" all at 100 mph 14.1 ( with the 2.5 60" 14.5 100 mph)

I planning on going to the track again soon. Should i run my 205/50/15 dunlop direzza instead with my stock itr rims?

What i'm trying to find out is which tire diameter would help me accelerate down the 1/4 mile faster 195/50/15 or 205/50/15 if everything was identical 60", track condtions and car. And why?

 

anyone knows?

 

uh you need a lot of help, as for tires with what you got use the wider profile tire, i cant attest to which are stickier but take a lot of pressue out of them, 40psi is way to much. try 23-25psi and see how that feels. dont worry about your trap speed till you get some decent ET's. cutting a 2.0 60' will give you a 13.8-.9 et.

 

so stick with the 195/50/15 not the 205/50/15 and set the tire pressure to 20-25?

 

yea you can start at like maybe 25psi and keep lowering it a few psi each run if you arent seeing improvements in the 60ft. im not sure how low to go on street tires, ,but id imagine not much less if any than about 18-20 psi

 

i hope you know that both the tires you mentioned are the same diameter, the 205 is just a little wider than the 195. so your trap speed isnt going to be effected at all by which tire you use. however like said before i cant tell you which of the two tires you have is the sticker of the two. the best way to tell is to check the sidewall for the treadwear number usually the lower the number the softer the tire is. and you definately need to lower your tire pressure down to around 23-25 like mentioned above. hope it helps. your best bet is to get a set of bfg's 225 50 15 and run around 12 psi in them. gl

 

300 treadwear on the dunlop Direzza DZ101 205/50/15

200 treadwear on the dunlop SP Sport FM901 195/50/50

so i should stick with the fm901 because of the lower treadwear right?

 

2 more days which tires?