1FooknTiteFD

I have 235/45/17 in the front and 255/40/17 in the rear. Thinking of going to 18's with 245/40/18 and 275/35/18 in the back. Does anyone know how this will affect the handling characteristics of my car, or am I better off sticking with the 17's?

in2twins

Good luck finding 18" race tires. There are some hoosiers for $$$$$, but no RA1, V7oo, V70a, Yoks, Etc. I currently run 235-40-17 RA1s on a 17x8 rim. I am going to make some flares for my FC, and run 275-40-17s on a 17x9.5" rim all around. I'll probably use Supra tt rear TT rims as I already have 3 from my Supra. You'll have to experiment with your shocks, and sway bars to keep the car from pushing, assuming your pretty neutral now. I run 255-40-17s front, and 275-40-17s rear on my supra. If your making a lot of power, you'll love the bigger rears as you may be able to exit under full power instead of waiting to get straight. Carl

specRX7_22

SRX7 ('81-'85) runs 13" wheels (most ppl use either panasports, diamonds, american racing wheels) on 205-60-13 Kumho Victoracer V700 or Toyo Proxes RA-1.

--eric

Silkworm

Kumho makes 18s in the Estca V700s. 265/35 and 285/30

Now, I would stick with 17s because of weight, I don't know of anyone making a decent race wheel in 18s that isn't the price of your first AND second born children.. A good CCW wheel is ~25lbs IIRC in 17x10

I run 15x6.5" stock wheels with 205/50/15s, moving to a max legal 15x7 Kosei K1 with 225/50/15 Toyo RA1 very soon.

PaulC

finky

iTrader: (2)

245/45-16 Hoosier A3S03s on stock fd wheels. I can't beat on them to much because I have to save them for auto-X.

rynberg

First of all, if you move up to 18s, you will need lower profile tires than that (unless using true shaved race tires). With street tires, you can run 245/35 or 255/35 up front and 265/35 or 285/30 in the rear.

Max Cooper runs 18x10 CCW wheels (which only weigh 21 lbs) with 285/30s on all 4 corners. SleepR1 ran 245/40 17 and 275/40 17 Hoosiers but is going to a different set-up for next year. I believe he is going with 265/35 18 up front and 285/30 18 for the rear.

Note that to go 18x10 up front (like Max), you will need aftermarket coil-overs with 2.5" springs. I think I've seen you post that you have the tein HA's, so you would be set there.

Rs4Racer

I was thinking about 225's on 16 x 7.5 wheels for an n/a. Would that be a good size?

Silkworm

That's fine if your race class allows 16x7.5 wheels.

SleepR1

This year the setup was 8.5 x 17 with 245/45-17 front and 9.5 x 17 with 275/40-17 rear. Wheels were SSR Comps. Tires were Hoosier R3S03

2003--if I have transport service to the track--9.5 x17 with 245/40-17 front and 10.5 x 18 with 285/30-18 rear. Wheels will be Volk CE28N. Tires will be Hoosier R3S03. If I have no track transport for 2003, and I'm forced to drive to and from the track--FIVE 9.5 x 17 CE28Ns with 255/40-17 Michelin Pilot Sport Cup Comps. The fifth wheel/tire serves as a full-size spare; I'll invariably pick up a screw or nail during my commute TO the track!

FWIW Your setup will create understeer. If you stagger the wheel diameters to allow for taller tire profiles up front (while maintaining the correct overall tire diameters fr/rr), you will dial in more oversteer for a more neutral handling setup. Understeer is a good thing, but not too much of it, such that you have a hard time turning in...

bradrx7

I run 18x19 Technomagnesio wheels with 265.650x18 Dunlop slicks all around.The Technos are very light at 17.5 lbs. each and Dunlop GT slicks come in 6 compounds and I run 'medium minus'. Grip is very good. <G>

SleepR1

Wow, Brad...you must mean 9 x 18 Technomagnesios, based on your Dunlop slicks' sizes. Converted to inches your tires are 10.4 inches wide x 25.5 inches tall x 18-inch wheel diameter? Nonetheless I'd like to see a pic Curious why you didn't go with Pirelli D5 compound or Michelin slicks (the Porsche Supercups have switched to the Michelins from Pirellis)?

bradrx7

Doh, I hit 19 instead of 10. They are 18x10. The tire is exactly the same size as the old 275/40x17 I used to run. The Dunlops are awesome tires with a very sharp shoulder profile.

SleepR1

Ahhh, makes sense now

Glad you like the Dunlops...

EProdRx7

where I race in EP biggest we can run is 15x7 with 10 wide slicks. BTW when I used to race a VW I started on 13x6 rims with 205/60x13 tires. I was given a chance to do some tire testing for Toyo and found that the car was faster on 185/60x13 tires. Just goes to show that bigger is not always better.

1RedR1and1RedPEP

Brad, do you have a good source for the dunlops? i have 18x10s also and would like to try the pure slick as as opposed to the V700s ive been using.
1R1

diyman25

UNLESS u have super big BRAKE or big pocket. the 17 are good enough for every thing. I will run 17x9 F/R with either 245 or 255. on MY ITE and FP race car

foko

i recently debated this decision and decided to go with the "cooper" fitment....that is 18X10 all around with 285/30 khumo v700. basically the pro/con list comes down to weight vs contact patch.

ccw, kinesis, fikse, forgeline, and probably others make 18X10 that weigh about 22lbs. v700's in 285/30-18 weigh about the same....so that's about 44lbs per corner. all in all a pretty reasonable number given the size of the contact patch you get. any fd making 350 or more rwhp will be fine accelerating that rotating mass.....of course another downside to the weight is the handling effect of the unsprung weight. i decided the extra contact patch off set this issue.

additionally the issue of lower aspect ratio effectively changing the spring rate may or may not be an issue for some.

all in all, i elected to maximize my contact patch. i'll let you know how it turns out if kinesis ever delivers the wheels....waiting for more than two months now and getting pissed!

fabian

Silkworm

fabian,

I need a loan Those are some expensive wheels you just rattled off..

Seriously though, why not 17x10? 285s will fit on 17s just as easily as on 18s..

Anyway, enjoy either way

PauLC

Chronos

wow, how much are those wheels?! I know the gold magnessium mazdaspeed wheels are extremely expensive...

bradrx7

1RedR1and1RedPEP... As for a good source, not really. I scour the tire dealers, like Sasco, for quallie take offs. You need to wait until right after a big GT race like Daytona to snare a quantity. Then, I bag them and use them up.

Chronos... The 18x10 (I made a typo when I said 18x19) Technos are in the same bracket as my old Kinesis which were stolen along with my old car and never seen again. Istill have my eyes open and the wheels serial number, hehe. Sooner or later they will appear. <wicked grin>

gfelber

Paul,

New CCWs are 19 lbs in 17x10 and 20 lbs in 18x10. I have the "intermediate" lighweight design (non-cheese-holed centers) which is 20.5 lbs in 18x10. Another reason the 18x10 is nice is that one can use 285-30-18s which, for some tires, are actually lighter (not Hoosier which is .5 lb more)than the 275-40-17s due to shorter sidewall (of couse there are issues with running such a short sidewall). You can maintain the stock diameter/circumference for similar gearing with this setup as well.

Gene

gfelber

For you guys concerned about unsprung weight, there is one other point worth mentioning re: tire weights. Kumhos, though less expensive, are much heavier than Hoosiers- even the new Ecsta V700. For example, in 275-40-17 the V700 Victoracer weighs a whopping 28.8 lbs, the Ecsta weighs 27.2 lbs, and the Hoosier R3S03 weighs 20.5 lbs. That's roughly a freakin' 7 lb difference with the lighter Kumho!

BTW- the Kumho Ecsta in 285-30-18 weighs 25.6 lbs.

Full blown slicks like Brad's Dunlops are even lighter than the Hoosiers.

Gene

bradrx7

Gene is correct regarding tire/wheel weight differences.

While I did not weigh the combos on a scale, while swapping the CCW 17"/Hoosier for the Tecnho 18"/Dunlop the weight differnence was noticable favoring the latter.

Also, John Purner at CCW has been offering 18" CCWs with Goodyear slicks for years. You hard core brethren may want to check with him regarding affordable tire/wheel combo deals.

rynberg

Actually, the CCW's are less than $2k for the set. No one makes a 285 tire in 17" diameter. 275/40 really only works for a race tire, 275/40 17" street tires are too tall

If any manufacturers made a 285/35 17 tire, there would be no reason to go to 18s IMO.

bradrx7

Uh, I believe this section is 'Race Car Tech'. We are discussing track only tire/wheel combos, not street 'bling-bling'.

Back on topic, I'm not sure you can fit any tire wider than 275/40x17 (or a 265/650x18 which is dimensionally the same) without flaring the fenders. Even then, you will need to run an off-center wheel and suffer the suspension problems that will occur.

It will probably generate enough grip to match the driver ability anyway. We all need to work on the driver as he/she is the biggest performance weak spot.