I am finally to a point where I am about to buy wider wheels and R-comps for my Street Mod Auto-X car. To get this out of the way I usually just run locally but do have grand visions of going to Lincoln for Nationals. These visions could be done as early as next year. The goal would be not to finish DFL.

That said, I am reconsidering what I had originally planned for wheels/tires. I had been planning on going to 18x10 RPF1 wheels to run some 285/30-18 Hoosier A6s. Recently I've been looking up specs on the new A7s to add to my original wheel/tire spreadsheet and noticed they run smaller than the A6s. The new measurements on the 285/30-18 A7 make me wonder if I should just stick to a 17" wheel/tire combo and save on the rotating mass. Specs as follow (per TireRack):

Hoosier A7
Size: 275/35-17
Section Width: 11.0"
Tread Width: 10.3"
Weight: 22 lbs
Diameter: 24.7"

Hoosier A6 (discontinued)
Size: 285/30-18
Section Width: 11.5"
Tread Width: 10.9"
Weight: 24 lbs
Diameter: 24.9"

Hoosier A7
Size: 285/30-18
Section Width: 11.5"
Tread Width: 10.4"
Weight: 24 lbs
Diameter: 24.9"

If I got 17x10 RPF1s w/ A7s instead of 18x10 RPF1s w/ A7s I could save 3.6 lbs per corner on rotational mass for only 0.1" of tread width. Anyone have any insights to help me decide?

 

If you look at the Hoosier website, the 285 A7 specs out at 10.9 inch tread width. http://hoosiertire.com/rrtire.htm

 

That's about all I needed. I feel silly now.

 

Not sure how hard you want it, but if I was building another SM car, I would try to fit the biggest tire I could. Even 285s on a car that makes 400+ HP will be border lining it. That said, there is also that game of max allowed weight depending on how wide tires are, which also plays important part of making decision on this.

 

315 is the new 285

 

Lol

 

I know it is but I don't think I'm willing to sacrifice my car's body in order to get there. I should have bought an Evo that was beat so I didn't care about it so much.

 

what is your target car weight? if you went all out in SM i bet you could get to 2800lbs.

i have 18x10.5 with 285/30 and 17x10 with 275/35 a6 and the 17" is quick! i personally like the added side wall of the 35 series tire on un-even surfaces.

 

2800lb is definitely doable in SM. The min weight with 275s and a 2.0 would be 2620, which I'd reason isn't possible within the class rules. The only reason I'd go down to a 275 is if I could hit minimum, and that's only if I were running 285s. Otherwise the wider tires (315 in my case) are the better bet.

 

You get those meats to fit yet, Rich? The first cut is the hardest

 

Still need to get a motor in the car first. Priorities.

 

Jesus. Are those 18x11

 

18x12

 

That's so 2013. 18x13 with 335 is what you need, lol.

 

Don't even tell me you're gonna try that lol. I think we're at the point of diminishing returns already.