Advice on track tire size
 

I know there are many threads devoted to the topic of track tires and wheel setups, but I specifically have a question regarding aspect ratio and ride height.
So I decided to get track-only wheels and tires and am going with the Enkei NT03+m in a 10.5x18 +30 on all four corners and Nitto NT01 tires.
My question is 275/35 or 275/40? The 275/35 diameter is 25.55" vs. the 275/40 is 26.65". I don't want to bottom out all over. Does it matter very much?
As for my car, I am lowered only on Swifts at the moment with SPL front A-arms and rear camber arms. Front camber is -2.6, rear is -2.1. Currently, I have had some inner fender liner rub with the stock sport wheels on 245 RE-11's at some tracks. Of note, at ZDayZ, some people mentioned my drop on Swifts looks a little more than others. I don't know if that is true, as I only know my car.
So, don't want to bottom out. Don't want to rub. 275/40 are $300/tire and the 275/35 are $259/tire.
What do you all think would be best?

I run 275/35R18 NT01 on 9.5 x 18" Enkei's (+13 at the rear and +25 at the front) on KWv3 lowered 20mm at the front and 15mm at the rear and and have no problems with bottoming out.

I also run a 3.9:1 diff ratio on longer tracks and 4.08:1 on the tracks with shorter straights.

If you measure from the bottom of your front and rear rims to the guard I can compare your ride heights with mine and tell you "how low" you have gone

In the FSM, there is a section which gives the OEM spec's but I was not able to quickly find it ... "search" may help your their

The 35 series tires will be quicker on the track & less likely to rub.
Lots of track guy’s run tires below 26”
PM Hotrodz; as one of his track setups are 18x10.5+30,,,unsure the tire size.
He’s putting down over 600whp...so he should be able to answer your questions.
:)

Thanks for the quick replies so far. Can you tell it’s been a slow night here in the ICU. I’m researching tires at 4am.

Hotrodz @Zdayz w/18’s strapped on,,,pic not good enough to zoom in on tire size.
https://uploads.tapatalk-cdn.com/201...13f1c82b7c.jpg


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On that set of rims I am running 295 30 r888. I have had no issues with rubbing at all. I also run a set of Volks in 18x11 +12 square with 315 nt01 square with no rubbing and I am lowered on Fortune Auto coilovers. I plan on running r888r 305 30 on my next set of tires for Enkies. They will be my street and wet weather tire lol.

damn Hotrodz, how do you not scrape your front coming out of drive ways and stuff

Lol, she scrapes all the time but my split is aluminum and so it just makes a lot of noise! I will probably end up raising her up a little higher but it still won't make to much of a difference....because racecar!

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im getting a splitter for my amuse bumper, im always scared that its gonna take my entire bumper off if it scrapes hard