Black R

This is for an EF application, but the tire size is going to be either 245/50/15 (R6 compound) or possibly 23.5 x 11.0-15/ 23.0 x 9.5-15.

I'm trying to figure out what width and offset to order.....

I was thinking that a 15x8 in a low 30 or high 20 offset would work, but perhaps I should even look into a 15x10 for the front?

This is for autox mainly; with the occasional lapping day.

I'm aware of the need to roll and cut the fenders, but am in search of more traction as I have exhausted my resources as far as suspension mods are concerned.

I know that rodney and others have gone as wide as they can with the A6 in a 225/45/15, with the 15x8.5. As a last resort, I'm willing to make that concession as well... in the REAR! :D

At some point, I am thinking the chassis won't allow the turning radius to accommodate too large of a tire under load where the frame rails come down in the front, etc.....

How extreme have you guys gone so far? Suggestions?

hybridmoments

i think you'll have to do more then Roll your fenders unless you are at a really high ride height

the 245/50/15 are like 24.4" outer diameter . a 225/45/15 is right around 23"
Not sure if the massive increase in OD from a 225/45/15 to 245/50/15 is worth the extra 0.2" of tread width you'd gain.

i have an EF . i was actually looking into running a 285/30/18 which is just barely larger then that 245/50/15 at 24.6" OD . but 10.9" tread width

i took the radius of that from the wheel center on my EF and using a marker made a line on the body of where the tire would be. lets just say it was a decent amount of metal that would have to be removed.
i have scrapped the idea for the time being but in the future would definitely consider the 285/30/18 as it really is the closed diameter you'll find while still having decent amount of tread width (10.9"). only thing is $300 per tire is not appealing.

along with BIG $$$ for some custom 18x10 Kodiak wheels

Black R

thank you for your reply.

i honestly think i got so caught up in going wider and wider that i didn't sit down, do the math and realize that 245 is only a tiny bit wider (.788") than 225 as far as contact patch is concerned..... But a 205 (8.07") tire is only a tiny bit skinnier than the 225... by .788".....!

Looks like I'll run this coming season on the 15x8 / 225's combo and concentrate on driver + getting the car set up to where I like it.

Just doing the calculations, a 225 is 8.858", a 245 is 9.646", and an 11" wide tire is 279.4mm.

I guess those 23.5 x 11.0-15 hoosier slicks would be a nice possibility in the not so near future..... although their recommended wheel widths are a little odd.

*edit*

the numbers published by hoosier are different than my calculations... perhaps because of the way the tires are constructed, or because they are measured on similarly skinny wheels?

https://www.hoosiertire.com/rrtire.htm

goodyear has a very slim selection in 15":

http://www.racegoodyear.com/pd...l.pdf

the G-19 comes in 22x9.5-15 (9.7" tread width on a 10"rim) or 22.5x11-15 (11.7" tread width on a 14"rim). only available in the r160 compound = soft.


Modified by Black R at 8:18 PM 12/1/2006

117

I have a pair of brand new R3S04 Hoosiers in 245/50/15 that I'd sell dirt cheap. They've been stored in our spare bedroom in plastic bags for a little over a year now. I don't plan to use them anytime soon, so I'd like to sell them.

shakedown94

could run a cantilever slick, hoosier 23x9.5x15 would fit on a 15x7. your car would be able to handle that better then trying to put on a 11" wide rim.

hybridmoments

#1 running a "slick" would put you in MOD class. you need an R compound to stay in Stock class, Street Mod, Prepared, etc.
i've heard some good things about the Nitto NT01. not as sticky as a V710 or Hoosier R6, but i've heard they last pretty well and don't need to be shaved. if you are running at the track and Autox then you might want to look into those cause you may get a full season out of a set.


#2 You need to look at the TREAD WIDTH measurement that the manufacturer provides, and not try to figure out the dimensions based off the given tire size.
it will not be accurate. alot of tires run larger/smaller then others and larger/smaller then their designated sizing. i know hoosiers run larger then kumho V710 in similiar sizes
just cause it says 245 doesn't mean that it is .78" wider then the 225.

based on hoosiers specs for the R6
225/45/15 Tread width 9" Section Width 9.8"
245/50/15 Tread width 9.2" Section Width 10.1"

So as you can see it's nowhere near 3/4" wider. if you went by the 225mm spec, they should be right at 8.86" and the 245 should be 9.64"
going by treadwidth the 225's actually run bigger, and their 245's actually run smaller.


also. if you ran the 245 the high OD " would most likely require you to change your Final Drive ratio in your trans. and don't forget about the extra 4 lbs per tire. not to mention the weight of a 15x10 rim compared to a 15x7 or 15x8.
besides HEAVY steel wheels, you'd have to get some custom made. so figure $400+ each for Kodiaks.
Unless you want some Work Equip 03 wheels. those can be ordered in up to 15x11 i think. but they are probably heavy bastards and they are $400 plus each anyway.

i'd stick with the 225/45/15 mainly for the cost, weight, minimum body work alteration required. and maybe some relatively inexpensive 15x7 Enkei RPF1 (about 9 lbs each) $180 each.

just from experience with friends cars and friends who work at race shops doing lots of race tire mounting, your fastest bet is to get tires with the most recent manufacturing date as possible. The longer the tire sits around the harder they get. especially if not in an airtight bag. don't buy your tires in january if you aren't using them til May.
i bought some unused/discontinued A3S04 hoosiers this past spring '06 cause Hoosier was selling them at discontinued pricing. they sucked. and they were unused. my friends new Kumho V710 were much much stickier then them. i wish i had just spent the extra $50 per tire and got the kumhos.


Modified by hybridmoments at 2:30 PM 12/5/2006

Black R

thanks again for your posts.

i noticed that about the treadwidth after posting, however i felt the links i gave were obvious.

as you can see i later posted the links to the goodyear site where the 9.5" wide tires actually have a 9.7" tread width when using 10" wide wheels.

117 has a good deal on the hoosiers, so I may just try them out during the preseason.

i found that work wheels seem to be about $400+ each when getting wider and wider..... although it looks like for my application (5x114.3) that the pickings are even slimmer... and there is the matter of A-disc, etc fitments (assuming the shape of the wheel spokes).

Since the 245/50/15's will fit on an 8" wide wheel, I may try that in the interim until I can figure out the best backspacing/ offset.

I already have a 4.9 final drive + close ratio gearset + stroker talldeck bseries motor, so the desire for wider tires is of necessity due to torque...

hybridmoments

well for the wide tires look into some custom rims, like Kodiak
15x10's are $426 each
http://www.kodiakracingwheels.com/wheel-prices.php

also the 245's on an 8" rim might not be the best setup. most people run the widest rim possible. mostly i've heard that it creates better turn in response . where as a wide tire on thin rim might not be the stiffest setup or have the most response.

from DUNLOP
"Wider rims may offer some performance advantages over narrow rims. A wider rim increases the distance between the beads, which results in a straighter sidewall, which stiffens it. This results in quicker steering response and higher cornering forces.

Negatively, the straightened sidewall transmits more road shock to the wheel and suspension, placing greater stress on chassis and suspension parts and delivering a harsher ride. The straighter sidewall exposes the rim, making the wheel more susceptible to damage.

A narrower rim pulls the beads closer together, curving the sidewalls. This increased curvature allows the sidewall to flex more readily over bumps and absorb more road shock during driving. This offers a softer ride"