Here's my problem:
Due to the fact that this lady in a van got into my lane, cut me off, and didnt speed up, I have to get some new tires.... my tires ended up getting a flat spot because my car just slid.
Anyways, i'm going to start getting into autoX and road courses this coming year but i'm faced with a tough decision. I was thinking of buying some good quality tires for my 18's to do the track racing, but then I thought of getting some 17's with some nice tires for the track, and some cheap tires for my 18's (daily driving). I really dont want to spend too much cash and I really like the look of the 18's on the car.

My question is: How well would my 18x7.5 rims do on a road course using a 235/40/18? Would I benefit more dropping down to a 17x7 or 17x7.5 rim and using a 225/45/17 tire!?
I currently have 235/40/18 Nitto555's tires, and when I first got them, I took a tight, underpass, turnaround that is two lanes wide going about 65, and the car handled perfectly... the car didnt slide or feel like it was gonna lose control.
Can you experts please help me out.

 

It depends on many factors, I don't think anyone will be able to tell what's better for sure...

As a rule of thumb, the most important thing is a tire compound, second goes the thread width.

But lower profile might play for or against you depending on the pavement, and sidewall stiffness.

Heavy 18s will, off cause, play against you.

Hope this helps...

 

GRM just did a text on with the same tires but in 16", 17" and 18" form. Same width too.
The tire that handled the best was the 17". Even though the 18's still had the same diameter with the tire mounted (shorter side wall), the rotational weight of the wheel actually slowed the car down.
17's are your best bet, plus 17's are usually a lot less expensive

 

that said, the GRM test was with a 3-series BMW, IIRC, which has quite different handling characteristics from the maxima.

that also said, I prefer a 17" wheel for track to an 18. A bit more sidewall to play with and lighter weight.

To the OP, keep in mind that the tires you use for the track are going to get torn up pretty good, so you probably don't want to use the same tires you use for daily driving. Get yourself a good A/S tire for the 18s daily driving and pick up some cheap 17s with Hankook 212s or Azenis 615s for the track. I prefer a 17x8 with 245/45/17 rubber...our front-heavy cars need a bit more beef up front than a 225 imo...as long as you're not constrained by classing regulations or anything.

 

^ What he said. I could tell a very noticeable difference when I went from my 225/45/18 Michelin Pilot Sports to some 235/40/18 General Exclaim UHP's. Next season I'm looking for something for my stock 16's, as the G 18's are just too damn heavy.

 

I'll second Irish's post 100%. the 18s are too heavy for track use, and the tires are more expensive. if you're going to be doing road course events, you're going to start spending lots of $$$ on tires. the cheaper they are to replace, the better. The difference bet equal tires in 17" and 18" For Nitto NT-01 is $47 each on discount's site. that's $188 a set.... when I was running R comps on the Maxima, I was going through a set a weekend at the track, so that's $132 a weekend I'm "saving" right there based just on the tires!

back to the point, I recommend picking up a set of decent 17" x 8 or 8.5" wheels and some good track tires.. then throw the cheapest all-season tires on the 18s you can.

 

You guys are right. It's my cheap side thats fighting with my logical side..hehehe
I'm still researching as far as what tire to get when I end up purchasing the 17 inch wheels. I'll have to get back to some of you for advise/opinions on specific wheel once I narrow down my selection.

 

^ I'd suggest looking for some used G 17's... Those can be had for fairly cheap. Just make sure you get matching widths.

 

If you want to stay with a somewhat long-lasting streetable tire, the RT-615 is a good choice. you gotta be smooth on the race track though not to overheat them and make 'em greasy.

If you want to get a bit more aggressive, look at the Nitto NT-01. I've used them as well as the Toyo RA-1 and like the Nitto MUCH better. they supposedly have the same carcass, but different compound and tread pattern- but I've found the sidewall on the NT-01 to be noticeably stiffer than the RA-1. with those tires though, you're going to have to run some insane camber up front to keep from eating the outer sidewalls off. something in the 4-5 deg range, which will throw your ackerman and bump steer all out of whack to get that much camber.

Whatever you use, make sure you get something with an EXTREMELY stiff sidewall and make sure they work well for nose-heavy FWD cars..

 

Matt, what do you think of Goodyear F1 and Yokohama Neova? Both of them seem to be at the top of every tire comparison list, yet I never see/hear people actually using them.

 

Yokohama's are good but darn expensive. Same for most anything made by Goodyear. My suggestion was gonna be a set of 245/45 Azenis from DiscountTire for < $500 new. Then I found this ad. $650 for used V710's AND wheels. (I think the Evo wheels work for us). I mean just take it easy til you get the hang of race rubber n all.
http://sccaforums.com/forums/thread/274614.aspx

 

For what's it's worth, I run a 16" on my miata now with a 215/45/16 and the rim is 7" wide. I am going to drop down to a 15x8 and run a 225/45/15, either Hankook(prolly) or Toyo in the summer once my current tires are toast....

I like the idea of going smaller with wider, rubber....

Also Miatas = Gay....cept mine 240rwhp FTW

 

no direct experience with the F1 or neova, so I won't attempt to spout BS.
I do believe one or both were tested in GRM's tire tests in the last year tho.

 

eh... 15x10" wheel with 275/35/15 hoosier a6. if you are gonna mess around with another set of wheels you might as well get something thats gonna be fun.

 

the general consensus from my friends and GRM is that the neova is all that and a bag of chips for street compounds, but you certainly pay $$$! The neova's would eat the goodyear f1's for lunch...but they are a good deal more expensive.

who makes a 15x10 with good brake cooling, ie, aren't mustang drag billet wheels?

I had the goodyear f1's, the sidewalls were really soft like my current toyo t1r's...wet traction was on par with the t1r's, the dry grip on the f1's was slightly better, although they were less communicative than the t1r's...they are also more expensive than the t1r's!

the evo wheels do work on our cars, if you can find someone offloading the bbs evo mr factory wheels they are a steal, as they are forged, lightweight and fit our cars perfectly...but that deal Brian/bejay posted is great, I ran 245/45/17 v710's last season and the grip is phenomenal (which is the size and tire in that deal)...

good tip on the nt-01's matt, I always wanted to know how they differed from the classically great ra-1's...