Wheel Size Advice

[jimw405]

I finally pulled the trigger on a car better suited to the track than my '11 Audi A4 and just got a '17 Subaru BRZ. It came with 17" x 7.5" wheels and 215/45-17 tires, and I'm considering a second set of wheels/tires for track use. I think I want to go up to 8" wheels to get a bit more rubber on the road. There are lots of 17" and 18" choices when I look on Tirerack for wheels that will fit my car. What advice would you have about sticking with the 17" OEM size vs. going up to 18". By they way, not sure it if matters in the decision process, but I got the Performance package, which has Brembos front and rear and stiffer Sachs dampers than the standard BRZ. Thanks for sharing any thoughts you have on this! Looking forward to getting on the track!

[paultg]

Jim, what class do you want to compete in for the time trial / season?
Personally I am sticking with 17" rims for my '10 MX5. I think the 18" dia means more expensive rims & tires.
Wheel width really depends on what you want to do for classification.

Paul G.

[jimw405]

The Showroom Assessment for my car puts me in T50 with 54.4 points (I'm assuming that the Performance Adjustment for my BRZ is 3.3, the same as I see for the 2012 FR-S and 2013 BRZ in the Showroom Assessment listings). Interestingly, if I run 225 width tires, Michelin Pilot Sport Cup 2s and my competition weight is 200 lbs over the showroom base weight, I'd come in with 49.6 points and be just in T40. Going down to 7.5" wheels/215 tires brings me in a point lower, but I'm not sure I need the point to stay in T40.

[peejay]

I believe the BRZ/FRS can fit a lot of rubber under the fenders so it depends on your goal. If you can find a way into T40 that might be good. Do you plan to do any autocross? Might be worth checking the maximum rim and tire width for a few classes in Solo. Paul is right in that 17" are usually cheaper.

I'm a fan of grip and knew that I wasn't going to run R-comps so I went with a 225mm 200TW tire on a 9" wide rim for my Miata

[962porsche]

there is a misconception about tire sizes . tires are not penises the bigger doesn't always mean better !
tires need heat to stick to the track it's about temps and what tires your running .
things like side wall size also effect how your suspension works or doesn't . as the side wall is part of your suspension .
thinks like keeping the rolling radius if say going from a 14 to 15 inch wheel but keeping the rolling radius the same may not effect your over all gearing but it could effect your suspension losing the suppleness over small bumps .

two years ago i was running stock 14's on my bone stock 93 miata with used up chumpcar take offs star spec's at thompson i had new 15's with new star specs same off sets as the 14's .
i did two runs in the morning finely corded the crap out of the tires and for the two after noon runs swapped my tires to new 15's with sticker star spec . the car was over 1 second slower per laps . even a few weeks later when i went back to thompson still running the 15's the car was never turning laps as it did on 14's .
in fact at every track the car was not turning laps close to the same times as it was with 14's on the car .
taking tire temps they could get to the 190 to 200 degrees the tires needed to work as they should . at best high temps were 160 average to cool to get good traction .
last season i installed cheap 399 dollar raceland shocks and spring kit on the car the spring rates are only 50 lbs more over the stock spring rates but the car finely is back to the same times as it had with 14's on the car .
side note the raceland shocks need more rebound valving !

so just going with bigger wheels and tires doesn't mean your going to turn faster laps . tires effect every thing braking , acceleration , gearing , suspension ,effects everything !

[gcranston]

I'm in a 2015 BRZ, wrestling with the same question as I get closer to burning through the oem tires with each track day. My plan is to stick with 17's to keep the unsprung weight down as much as possible. I'm looking at Enkei RPF1 17x8 with 235/40R17, probably hankook rs3 or nitto nt05. The ft86 club forum has EXTENSIVE fitment info:

http://www.ft86club.com/forums/showthread.php?t=7535

Though if I can manage it I might go for gramlight 57xtreme, but that's my vanity talking.

[jimw405]

Graham, I just ordered a set of 17x8 RPF1 from TireRack. After much debate and discussion with one of their sales consultants, I went with 215/45 Bridgestone Potenza RE-71. Could have gone up to 235 as you suggest but TireRack consultant was pretty adamant that the 215 on 8" wheels would give much better steering responsiveness and the RE-71 are the best of the TW200 options. They were also less expensive. I'm going to give that a go. We'll have to compare notes!

[gcranston]

Trying to concentrate resources on driver-mod before car-mod. Going to drive the OEM tires off it first, then upgrade. Couple more days left in these tires for sure. Look forward to hearing how you make out.

[paultg]

I just tried the RE-71R on my 2010 MX5 at Palmer. It's pretty sticky. I'm on 215s as well but on a 7" wide rim (factory mazda wheel).

I think you'll like them. I felt they got a bit hot / greasy (car is 2600-2675 lbs). I had stepped down from 225 NT01s though.

Paul G.

[gcranston]

Thoughts about the RE71R versus the Nitto NT05 out hankook rs3? It's my daily drive as well. I have dedicated winters. My concern is short life and hydro planing. I know both are worse with the nitto but I'm not sure how much worse. Is it manageable?

[ED9man]

The RE-71R is supposed to be the best tire in that category now. Any max performance street tire has a shorter life in general. They are definitely the cheapest and longest lasting track tires though. Like any other tire when the tread gets low they become more prone to hydroplaning. I've run these types of tires for years on my street cars and as long as you don't drive on them when it's super cold out, they are just fine.

[gcranston]

Awesome, thanks.

[peejay]

I just tried the RE-71R on my 2010 MX5 at Palmer. It's pretty sticky. I'm on 215s as well but on a 7" wide rim (factory mazda wheel).

I think you'll like them. I felt they got a bit hot / greasy (car is 2600-2675 lbs). I had stepped down from 225 NT01s though.

Paul G.

Hi Paul,

Why the change from the NT01s? I assume points.

[paultg]

Correct, to class down into T40. The RE-71Rs wore pretty fast. I'll take some pictures and see if I can post them. - Paul G.