Noob alert! Is a 7"wheel out of the question for autoX?

[RCV7]

I have access to a set of LTW Kosei K1 16X7 wheels I'd use for AutoX. They weigh about 15 lbs each. Are they too narrow for autoX and track use?

Update below:

[bullmand]

Short answer is no, but it depends on what class you want to be in/what your goals are. The stock wheel on the sport package is 16x7 and they came with 225 width tires. Those worked just fine for me for several years of autocross. As a point of reference, Spec E30 racing is done on either 6, 6.5, or 7 inch wheels and they don't seem to have any problem getting around a track. There's also an apocryphal statement that's usually attributed to Will Turner (maybe T.C. Kline, I can't remember for sure) in which he stated that 16x7 is the perfect size for the 318ti. I don't know if that statement was ever made or in what context but there it is. If your access to these wheels is free or cheap, and especially if you're just getting started with autocross or track events, you should probably go with these to get started. Use whatever money you don't spend on the wheels to get some good tires and go from there. I think you'll be just fine.

[familytruckster]

They'll be fine.

I run autox with a 4500lb wagon on 8" wheels with mere 245's, and it gets around pretty darn well.

[slow_ti]

That's perfectly fine.


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[spidertri]

Has anyone run into bent wheel issues with the 16x7 koseis? I've read that the 17's bend pretty easily when using them as street wheels.

I've been looking for a lightweight oe 16" wheel and have come up with:

16x7" Style 32 et46 @ 15.9lbs
16x7" Style 46 et47 @ 16.3lbs
16x7" Style 360 et31 @ 17.6lbs (I like the offset of this wheel)

Compare those to the stock sport package style 18 16x7" @ 20.6lbs.

Anyway, do you guys think I should try and find an oe wheel or a kosei for mostly autox use?

[bullmand]

Given the price of the Koseis in that size they're nearly disposable. I have limited personal experience with them, but the 15" set on my buddy's SpecE30 car seems to be holding up just fine.

[cooljess76]

16x7's will allow you to run a larger sidewall than a 17, thus giving you a little softer ride and better rim protection. I've bent plenty of 17" wheels due to potholes running 40 series tires, but with a 50 or 55 series aspect ratio tire, you'd have to hit a curb or something to bend a wheel. Like bullmand said, Koseis are pretty inexpensive and to my knowledge they're one of the lightest wheels available in that price range. For the price you'd spend on a set of 4 OZ's or BBS, you could probably get 5 koseis fitted with good rubber.

[spidertri]

For the time being I'm running my stock 15x7 style 18s at autox (but dang, they are heavy wheels for 15x7!). I figure I'll keep an eye out for a set of kosei 16x7s for next season and then run some grippy 225/50 tires.

I was mainly wondering if anyone had experienced 16x7 koseis bending while using them on the street. While they are inexpensive, I don't plan on buying a new set of wheels, just finding a deal on a used set. I like considering oe options because they are (hopefully) made to a higher standard than aftermarket wheels.

[cooljess76]

Dave check these out:
http://forums.bimmerforums.com/forum....php?t=1696632

[spidertri]

Ah man, those would be nice.

I'm conflicted because I just saw these too, didn't even know they existed. 16x8 et38 16lbs http://forums.bimmerforums.com/forum....php?t=1696327

[mohaughn]

You'd be better off getting the E30 M3 15x8 K1s. The 16x7, or really any 7" wheel is to narrow for just about any 225 r-comp tire. I ran a 17x8.5 K1 for a few years and never had any problems. And my track driving consists of about 80% sebring. If any track is going to bend a rim, that would be the one.

If you are in a street tire class, you can squeeze a 225 onto a 7" rim, but on an r-comp I've found that a 225 R888, NT01 and Hoosier conti-spec are to pinched to perform well on a 7" rim. You end up having to run a 225x50 which has way to much sidewall flex to give crisp and precise steering feedback.

I hunted and hunted for a set of SSR comp 15x7's because it was the lightest rim I could find. Now I wish I had listened to some other folks who said to skip the lightest rim and go with the wider 15x8 K1 that is like 2 pounds heavier.

The extra 1" of width and the subsequent wider tire contact patch will overcome any advantage offered by 2# of weight savings. The only downside is the increased scrub radius by running a wider offset wheel. I've not sat down to do the math to see how much impact that has on our cars. You can find some porsche people complaining of weird handling issues with +20mm offset rims or spacers.

[RCV7]

Thanks for everyone's input. Great info. I went with SSR Comps. 7.5 up front and 8" rears. Man, are those lightweight wheels. 225x45x17 all around Hankook Ventus V12 Evo which took 2nd place in this round up: http://www.caranddriver.com/reviews/...12_evo_page_10

[mohaughn]

That is a two year old tire review. Even though it does a good job of rounding up the current crop of tires, I think there are some better tires out now that that test does not cover. 225x45-17 Z1 star specs are a great tire. Probably cost a little bit more than the V12.

If you start to want to get seriously competitive, you'll probably want to go to a square 8" setup all the way around. Pushing a staggered setup hard at corner entry can result in excessive push. The rear will tend to have more grip and overdrive the front. Driving style can be easily adjusted to deal with it.

[spidertri]

While it won't be until next season, I was planning on trying to get a set of those 16x8 BBS RKs and going with a 225/50 street tire. Something like a Star spec, Hankook RS3, etc.

mohaughn, you mentioned the 15x8, what size tire are you running on that?

For autox does the M44 have enough power to utilize a 245/40-17 setup?

[mohaughn]

I'm still running the 15x7 with a 225 continental challenge take off "hoosier." I would run a 225x45 hoosier R6 on the 15x8. I've had to back off on my track events due to family life and not really having the time to properly prep my car for a lot of events, so my winter tire testing plans are pretty much on hold at this point.

I felt a 235 was to much tire for the M42, but NASA TT rules penalize you for going to larger width tires. SCCA Solo rules allow for much wider tires, and the hardcore autocross guys seem to love running the widest tire they can fit.

Finding the right and fastest tire for a particular car and driver can be a challenge, and you can easily spend a few grand buying different wheels/tires to test on.