Wheel tire setup for auto x/road race

[5.Shark]

I know a common setup is 18x10 sq setup because of weight savings, tire options, price etc.
My question is, would there be any benefit of the 18" setup vs a 19" setup assuming weight and overall price is the same? And wheel/tire diameter is also about 0.5-1" difference depending on tire choice.(between 26-27") Also the 18 would have more meat on the sidewall which I know is generally not wanted for the corners but I've seen some people have better results with a slightly taller sidewall.

Current setup.

-19x9.5 rtr wheels wrapped in 275/35 rubber
-Eibach sportline springs, adjustable sway bars
-Koni yellow shocks/struts
-maximum motorsports castor/camber plates
-whiteline LCAs
-J&M adjustable panhard
-Brembo brakes



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[noldevin]

18s will almost always be lighter (especially if you do a fair comparison of the same style wheel), the tires are typically lighter as well.
That being said, many are now doing 19x10s or 19x11s since some nice 200 treadwear tire choices are now out in 275/35, 285/35, and 305/30. The key is to get a nice lightweight wheel like forgestars.

 

[5.Shark]

That's actually what I'm looking at
The cf5/f14's in 18x10/11 or 19x10/11
Generally the weights/prices/overall diameter are pretty close for the tire sizes I'm looking at, 19 sizes were generally heavier but they also have a larger variety of 305 width
I looked up multiple combinations of wheels/tires
Michelins producing the lightest weights (based on tirerack.com info)
I can post up a picture of all the combinations later just in case it helps anyone out down the road


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[noldevin]

Posting up the weight combos is a great idea.
From what I remember, the sizes are within a couple pounds of each other.
The bigger difference is that the tires do not get lighter (and in some cases get heavier), and that weight is moved further out on the radius, which creates a stronger rotational inertia effect.

All in all, as long as you're going with light wheels and good tires, I imagine the differences are minimal. Especially with some of the awesome choices available in a 305/30/19.

 

[5.Shark]

Here's the compilation of tire data.
All info was taken directly from tirerack.com, discounttiredirect.com, and nittotire.com.

Michelin pilot super sport
Tire. Weight Diameter Price
295/35/18. 28lb. 26.1" $317

285/35/19 28lb. 26.9" $303
305/35/19. 30lb. 27.4" $341

Nitto NT05
275/35/18. 28lb. ~26" $242
275/40/18. 29lb. ~27" $192
295/35/18. 30lb. 26.18" $232

275/35/19. 29lb. 26.65" $251
305/35/19. 34lb. 27.44" $308

Nitto NT01
275/40/18. 30lb. 26.65" $277
305/35/18. 33lb. 26.4" $308

285/35/19. ??lb. 26.89" $???
305/30/19. 32lb. 26.26" $363

Nitto NT555RII Road Race
285/35/18. 29lb. ~26" $313
305/35/18. 31lb. ~26" $329

Contisportcontact 5P
295/30/19. 27lb. 26" $294
305/30/19. 28lb. 26.2" $287

Sportcontact 6
295/35/19. 34lb. 27.1" $354

S-04
285/35/19. 33lb. 26.9" $236
305/30/19. 33lb. 26.3" $274

RE-11
285/35/19. 31lb 26.9" $298
305/30/19. 32lb 26.3" $315
325/30/19. 35lb 26.7" $347

RE-71R
275/35/19 30lb. 26.6". $300
305/30/19 31lb. 26.2". $353



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[5.Shark]

When I get the chance I'll post up total wheel/tire weight and costs for each combination
I think based on cost,performance and aesthetics I'll be going with the 18x10/11 cf5 with nitto nt05s which has a total weight of 205.2lb, wheels from AM are $1560 with discount and tires are about $850 total.
Although the larger variety of 305 is hard to pass up with a 19" wheel...
What to do what to do...?


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[5.Shark]

I used weights for CF5 18x10/11 and F14 19x10/11

CF5 18x10 21.1lb 18x11 22.5lb
F14 19x10 24.5lb 19x11 25.5lb

Weights may be off because I was not able to weigh each of these and had to rely on other people's info but based on what I could find I'm assuming the weights are pretty close. *Price is only

Michelin pilot super sport Weight Price
CF5
295/35/18 *Lightest* 199.2lb $1280

F14
285/35/19 216lb. $1288
305/35/19

Nitto NT05
275/35/18 *Least $* 205.2lb. $848
295/35/18

275/35/19 226lb. $1118
305/35/19

Nitto NT01
275/40/18. 213lb. $1170
305/35/18

285/35/19. 224lb. $???
305/30/19.

Nitto NT555RII Road Race
285/35/18. 200lb. $1284
305/35/18.

Contisportcontact 5P
295/30/19. 208lb. $1162
305/30/19.

Sportcontact 6
295/35/19. *Heaviest* 236lb. $1416
*Most $$$*

S-04
285/35/19. 232lb. $1020
305/30/19.

RE-11
285/35/19. 226lb. $1226
305/30/19

285/35/19. 232lb. $1290
325/30/19

RE-71R
275/35/19 222lb. $1306
305/30/19

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[noldevin]

The NT05s will be a decent learner tire, but as your skills improve you'll be left wanting better. So definitely don't build your setup around those tires.
All the 200tw tires in 285 and 305 are honestly why i went 19s, the choices for 18s didn't impress me. The nittos are quite inexpensive, but its for a reason.

IMO, if you're going to spend the money on a road course tire setup, do it right the first time. Oh and don't do staggered, keep it square.

 

[5.Shark]

Yea the 19s definitely have more options, especially in the wider size tires
What's the widest you run on the fronts? Supporting mods if needed?


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[noldevin]

I run 285s on the front and I can rotate. Vorshlag sells kits for 11" wheels with 305s up front, but you need a fair amount of camber and the offsets are different front and back, so you can't rotate tires.

 

[OX1]

18's are pretty hard to fit even the 4 piston front calipers that 2015+'s
Gt's have stock (which I assume would eventually be somone's "minimum"
for running any road course).

I have 18's already and they don't make the bullet's in 19's,
the same as I have now, to use those brakes (only 20's, which I
definitely don't want).

Will take a 3/4 inch spacer, some light caliper grinding and longer studs.
I'm fine with it as mine will never see any road course.

The stock 15+ 18" wheels may also work (though they are not that wide),
as they run that caliper stock, but will still need a spacer, as the rotor hat on 15+ protrudes much further out than 11-14.