Track Wheel Setup Advice

[RoccoB517]

Hey everyone. I'm getting ready to change my track wheel setup, and I wanted to get some advice. As a disclaimer, I've done a LOT of reading on wheels and tires and I have been racing long enough to know that the ideal situation is to adapt the setup to the track and conditions. However, I'm tight on funds and want the best "all around" setup I can get. What I'm really looking for is some real world experience to help with my decision. Thanks in advance for any insight you can offer.

The car:
E30 w/M50 swap (supercharged)
Around 325whp/280tq
GC Coils (front rate 600, rear rate 800)
Full Cage
22mm Front Sway Bar
No Rear Bar

Running Time Trials in the Southeast Division (Road Atlanta, Roebling, Talladega GPR, Barber, hillclimbs, etc.)

Here are my options for wheels/tires:

275/35r15 Hoosier R6 on a 15x10 Steel wheel
Wheel weight=21 lbs.
Tire weight= 20lbs.
Tire width=10.1"
Total Weight Per Corner=42 lbs.

275/35/15 Hoosier R6 on a 15x9 Wheel
Wheel weight= 14.2 lbs.
Tire weight= 20lbs.
Tire Width= 10.1"
Total Weight Per Corner= 34.2 lbs.

245/40r15 Hoosier R6 on a 15x9 Wheel
Wheel weight= 14.2 lbs.
Tire weight= 19lbs.
Tire width= 9.6"
Total Weight Per Corner= 33.2 lbs.

I'm apprehensive to put the 275 on the 9" wheel because I feel like I might not be able to utilize the full potential of the tire. What I really can't decide is whether the 1" wheel width and 1/2" of tread is worth the extra weight. I'm leaning heavily towards the 245 on the 9" wheel.

[MX339]

I really don't think it'd be worth taking a 28 pound penalty in unsprung weight just to get that extra inch. I would think the weight would really nullify the small benefit of getting a little bit of a stretch. The sidewall of a Hoosier is already so stiff anyways I can't imagine it'd make that much of a difference.

Are you going to incur any classing penalties for running a wider tire? I know Jb325is was running the 245/40/15 on an 8" wheel so he may be able to give you some feedback on how they feel when being used on the minimum recommended width. I've got his setup now, but haven't been able to use it yet so I can't speak on that front.

Hopefully some guys with more experience with Hoosiers will chime in. It seems like the 275 on a 9" wheel would be your best bet.

By the way, are you doing any TT's with NASA? I'm usually at just about every NASA-SE event and it's nice to see any other E30 guys out there.

[RoccoB517]

Thanks for the reply. I'm currently driving in SCCA TT events. The NASA events generally seem to be a bit more expensive. It also seems that based on the NASA classing that my car would be in TT1. I'm not sure that I could be even remotely competitive there.

[Artful Dodger]

I have the same setup that MX339 is talking about. These are the R80 if I am not mistaken.

I ran them on 8" wide wheels. They are 245/580-15. I think they would be better suited on a 9" wheel. they worked great on the 8" but I think a 9 would be better get you a little straighter sidewall profile.

I think a 275 belongs on a 10" wheel. But if it is better for you to run on a 9 then do it.

Have you considered an alloy 10" wheel? Im sure you have. they are probably cost prohibitive.

[RoccoB517]

I have the same setup that MX339 is talking about. These are the R80 if I am not mistaken.

I ran them on 8" wide wheels. They are 245/580-15. I think they would be better suited on a 9" wheel. they worked great on the 8" but I think a 9 would be better get you a little straighter sidewall profile.

I think a 275 belongs on a 10" wheel. But if it is better for you to run on a 9 then do it.

Have you considered an alloy 10" wheel? Im sure you have. they are probably cost prohibitive.

After seeing some 275 Hoosiers on 9" wheels I tend to agree that they belong on a 10" wheel (outside of an autocross environment, anyway). I'm worried that the 275 on such a narrow wheel will screw with the slip angle too much in higher speed cornering. I'm hoping someone can chime in with their experience there. I'm somewhat convinced that the 245 on a 9" will yield the best handling, and possibly the fastest times of my options.

I have considered alloy 10" wheels, but I just can't afford a custom wheel, and I certainly couldn't afford to replace one. Especially considering the money I will be spending on tires. I'm trying to do the most that I can with what I have to work with, so for now if I want a 10" wheel it will be a 21lb steel wheel from Bassett.

Since I'm running in a "Street Unlimited" class with SCCA, I have LS1 swapped 240sx's and 400hp Evo's to compete with. I'm about 2-2.5 seconds off the pace. I plan on lightening the car by about 200lbs., adding the supercharger to reach the above posted hp/tq numbers, and upgrading from my current 15x8 225/45r15 NT-01 wheel/tire combo.

These wheels/tires are the last piece of the puzzle for me.

[klodkrawler05]

assuming no classing penalties for running the 10"/275 combo I'd do that, at the power levels your trying to get to the 15x10/275 isn't any heavier than the 17x10 type setups that e36's run. start optimizing the car for the widest/stickiest setup you possibly can then down the road upgrade to a set of lightweight alloy wheels to save the sprung weight, heck you might find a used set for cheaper later down the road anyway.

you will absolutely be faster on the wider 10/275 setup vs the 9/275 or 9/245, while you'll be fairly hard pressed to notice a 7lb weight difference per corner.

[Nsquared97]

Check out these 15x10's from Jongbloed. Not sure what they weigh, but definitely budget minded andshould work great with a 275:

http://philstireservice.com/

[RoccoB517]

Check out these 15x10's from Jongbloed. Not sure what they weigh, but definitely budget minded andshould work great with a 275:
http://philstireservice.com/

Thanks for the suggestion. I saw the group buy for these a long time ago, but didn't know that they were out yet. I ordered them the other day, and they should be in my hands on Tuesday. I'm going to have to work out the fitment with spacers, especially in the front, but they are still a much lighter option than the steel wheels even with the addition of spacers.

[robgoesvroom]

Thanks for the suggestion. I saw the group buy for these a long time ago, but didn't know that they were out yet. I ordered them the other day, and they should be in my hands on Tuesday. I'm going to have to work out the fitment with spacers, especially in the front, but they are still a much lighter option than the steel wheels even with the addition of spacers.

Let us know what you come up with for spacers and tires... I just got mine but am out of town to sort this out