I have a set of RPF1 (18x9.5 & 18x10.5 +15) wheels coming this month and looking to run Yoko Advan AD08 tires. I originally plan on running 245/35 & 275/45. Now after looking at the AD08 size sheet (Link) a 275 is not offer. They do offer; 255/35, 255/40 and, 265/35. I plan on using these wheels for road racing. What are your thoughts on the sizes?

 

285 front and 295 rear would be my track tire size in this brand.

I woud look into NT05's , they are cheaper , stick well, probably better , and have better sizing for the Z.

 

Don't think a 285 will fit on a 9.5 wide wheels. lol Also I want to run Yokohama's as I might be picking up a sponsorship.

 

A 285/35 will fit on the 18x9.5 with a little bulge. I'm running a 275/35 rear tire on a 9.5" wide wheel and it has a flat/flush sidewall with the wheel.

 

265/35/18 or 285/30 18 F and 295/30/18R would be my suggestion

 

Front = 255/35/18
Rear = 285/35/18

 

Here are the sizes available in an 18 guys;

225/40R18, 225/45R18, 235/40R18, 245/40R18, 245/45R18, 255/35R18, 255/40R18, 265/35R18, 285/30R18, 295/30R18.

 

I'd use 255/35F and 265/35R... no doubt about that. at least for the first "test fit".
from my experience with +18 offsets if your car is pretty low you'll need about -3 degrees of camber front to be on the safe zone and -2.2 in the rear (assuming your fender are rolled/cutted). than you can just measure and eventually switch to 285/295 combo... that is going to need 0.6/0.7" more of clearance per side.

 

+15 offset on the rims....
on the track better a smaller tire but good angles on the wheels than wider and angles like crap.

that is going to be so close to the fenders that is going to be a nice "game" finding the right height and angles.

I'd put the "small" one first and than check the clearance.. and eventually start raising the car until he finds the "sweet spot" where he can fit them right.

 

It'll be tight given the offset, but I'd hope to fit 285/30R18 FR and 295/30R18 RR. Start by ordering the 285s and try them on the front. If they can work - score, if not use them for the back. At that offset, fitting a large tire will be a challenge, so may be camber and suspension dependent as to just how large you can go. I passed on the +15s myself in the RPF1 for this very same reason, and am now running the even-lighter SSR Comps in 17x9.5 +30 all-around with 275s.

 

RPF1 is a great aggressive street wheel , but the fitment sucks for the track. I would have NT03's or different

 

man... I use 275 with +18 offset... they fit, front AND rear with track "spec" angles. and I'm damn low... so it can work... but 295 in the rear is going to be 13mm (1/2inch) more outside than mine... and that requires FOR SURE rolled fender and a decent height off the ground.

he can start with 255/265... it's plenty of tire to go out and have fun...
with a TT setup and UHP tires he has to be careful with the throttle regardless... no matter if he has a 265 or a 295...
besides.. better have a 265 with -1.8/2 degrees of camber in the rear than a 295 with -3 degrees... all it matters is the contact patch on the ground.

I went on the track with 235/245, 235/255. 245/255. and now 255/275 and I'm still able to push over 1.2 lateral G (actually more than 1.25).

consider also that if he'll come at TWS in the summer.. expect more than 90 degrees if not 100... with a TT Z, if he has to be easier on the throttle is better for the engine life, for sure.

 

^^^ Great info!!! Oh and I DO plan on coming out to TWS this summer. I'll be at MSR next month for the Texas Z Party!

 

I'll probably be there too. wow, I just hope to have enough tire and brakes for the TZP @ MSR. this set HAS TO last at least 3 events, before switching to R comp.
I never drove there... will be a lot of fun.

*edit* really... I guess you never driven this build of your car on a track, so I'd run "safe".
easy angles (let say -1.5 to -1.8 rear and -2, -2.5 front camber. front 0 toe, rear 0.1 degrees toe in) something that is going to advise you of any lost of traction and have a good grip for acceleration.
your car has 130hp more at the wheel than mine and I guess a shitload of torque in the middle with almost no lag (If I remember how the jwt tt works).
you really want to play safe. if not for MSR, for TWS where I'm pretty sure you can hit 145/150mph in the front straight and way over 120 in the back one and the corners are pretty quick.

 

Perfect sizes for 9.5 and 10.5 IMO...

245/275 ends up being slightly stretched and is better on a 8.5 and 9.5 setup while 265/295 is perfect for 10 and 11. That's for no bulge or stretch which is how I like my tires...

My favorite calculator for this type of stuff:
http://www.wheelsmaster.com/rt_specs.jsp

 

Well I've never adjusted any of the alignment settings. So if we could meet up I'd love to pick your brain more for what you think would work best. Also do you do these adjustments yourself?

 

any time at lunch (11/12) or after 5p.m. I'll p.m you my cell phone and my email.
no. I don't do those adjustment by myself. but I know at least 3 good shop with reasonable price for track alignment in 2 side of the town.

I work on the north side... so for me is decent for lunch around hooters on 1960 and 45, and in southwest (where I live) around bw8 and westheimer.

 

true on paper, but each tire size could change almost 1/2" between brands... there isn't a way to tell before installing them or check with somebody that already installed those tires.

on a 10.5 rim I'd go at least 275 is possibile and you can fit a 305 easily.
on a 9.5 anything between 245 to 285 is possible and "safe" for the track.

but again, using +15 offset is going to be a tight fit.
I don't know if robert has camber arms upfront and seeing my setup and how I wear the UHP tires on the track angles are going to be critical with an offset so aggressive.

I already know that with +18 offset in the rear, a 275 R compound that is a little bit wider than my 275 uhp (measured on a 9.5 rim like mine) I need cutted or flush rolled fenders to fit without going to a really aggressive rear offset (-2.7 or more) and I don't want.
upfront is going to fit with -3 degrees.. really close but fit.

 

Good point...I guess I'm just assuming exactly 255/285. I know you can fit a ton of sizes on a single width, but for me I like it to be as flush as possible...no bulge/no stretch...just my preference.

 

Ataru074: Just checking out those 255/35 & 265/35 tire sizes. The 255/35 states; "Package will stick out 30 mm (1.2'') farther (vs OEM). Make sure that you have enough room under the fender. If not, consider narrower tires or higher offset."
The wheel/tire calculator won't let me choose a 265 for the rear 18x10.5. However the 285/30 states; "Package will stick out 45 mm (1.8'') farther (vs OEM). Make sure that you have enough room under the fender. If not, consider narrower tires or higher offset."

OEM Wheel Size: 18x8.0 +30 F&R.