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SicMonte
10-23-2006, 09:30 AM
this past weekend..i attended my first autocross. I didnt get my car ready in time to make it on the track...but i viewed it and learned alot. Now I have some questions for you all out there that do auto cross.

As far as wheels/tires go...I have 17's on my car now (1988 monte carlo ss) with 245/45/17 out front and 315/30/17 in the rear. These are on torq thrust 2 rims. Here is what im thinking...I would want to get some R compound tires and rims to go along with them. I have had good luck with the toyo RA-1 tires...but the rears are only available in the widest of a 255/50/16. Does it make sence to go with a smaller size tire...but with a better rubber compound at an autocross?? They make a 315 in an 18 inch size...but i dont really want to go out and buy a new set of 18's. The 16's I was looking at are a set of Diamond racing wheels. I had these on my scca spec rx7 and loved them. What would you all do??

Also...the diamonds are drilled for a 5/8" wheel stud. Would it be possible to drill out my TT2's to fit that stud...or would the new lug nuts not work with that?

MrQuick
10-23-2006, 03:36 PM
auto x styles vary so you will get a lot of different answers.

IMO 255's should do fine. You don't want too wide a tire. Your rear end move a lot on small coarses. Having that extra space will be a god send. Can you run the same size all the way around? Another plus cause you can rotate them.

not sure about the lugs...are the Diamonds hub centered?

mpozzi
10-23-2006, 06:18 PM
As far as tire selection . . . we've been quite happy with the Kumho V710's. They're very sticky, last a long time compared to Hoosiers, and offer several sizes for us with larger American iron that want to go around corners quickly.

Mary Pozzi

David Pozzi
10-23-2006, 07:04 PM
16" tires are limited. The 255-16 is an OEM corvette tire, that's why it's still around. 17" rims have a better selection, especially in autocross compounds. Kumhos are about the cheapest and are very very good.

You need as much front tire on your car as possible, and the rears should not be too much larger than the front's, I'd say not much more than 1 size larger.

I would not go with 5/8" studs. Go with either 1/2" studs or metric 12mm studs. You can probably fit those studs on your street wheels with just a lug nut change. The 5/8" will require you to machine out the wheels and there are probably no to fiew lug nuts available in a 5/8" size. I have a pair of wheels machined out for 5/8" and they don't look very strong anymore.

SicMonte
10-23-2006, 08:12 PM
here is a link to the diamond wheels... http://www.diamondracingwheels.com/RoadRaceSeries.htm

it says that they are lug centric.

What wheels do you all recomend in 17's? mpozzi what sizes are you running??

i have a cage and alot of suspension work done (by SC&C)...and the rear has a frame notch to allow for 315/35/17 tires. The fronts can hold a 255 at the most....so would it be bad to have a bigger tire in the back??

David Pozzi
10-23-2006, 10:10 PM
Yes, get 17's if at all possible.

You can try the larger rears but you may need a larger rear bar or a small amount of additional rear roll stiffness assuming your car is well balanced on the road or on a race track now.

Autocross turns are often very tight and there are a lot of factors that put extra load on the front tires that you don't see on a road course or on the street.

A long wheelbase car will have the front wheels turned sharper than a short wheelbase car. High front end weight bias is another handicap to good cornering. Quick left right turns is tougher with a high polar moment of inertia and that puts extra understeer loads on the front end more than the rear.

My wife's Camaro has 245/45/17's front, and 285/40/17 Rear.

Our autocross rear tires are 245/45/17 8" wheel, front 275/45/17 on 9.5" wheel rear, and we still have a bit of understeer we need to fix with more rear bar. We will move up to 275's on 9.5" wheel on the front next.

Another thought is, stickier tires tends to help the lighter loaded rear tires more than the front tires, this also promotes understeer.

If what I'm saying is making you think you are going to have a ton more understeer, the answer is NO. I'm just listing some factors that come into play and they don't all add up to terminal understeer, just a mild case of it when compared to larger radius turns where you have more time to rotate the car and the front wheels are turned just a couple of degrees instead of near full-lock.

I'd just try to get the most front tire under it you can, run your 315's on the rear and look at a 275 front tire, it's probably pretty close to a 255/16 in width/dia, but I haven't looked at the charts to confirm that.
David

SicMonte
10-24-2006, 07:09 AM
do you have any recomendations on a 17" wheel...that would be good for auto crossing?

and can u explain understeer???

slowcamaro
10-24-2006, 08:56 AM
How far do you want to take it? How much do you want to spend? If youre getting a disegnated set of race wheels and tires you might as well go all out and get kuhmo 710s or hoosiers.

CCW makes a good set of wheels that are fairly light. As does Forgeline.

Here are some more wheels....

http://www.racerpartswholesale.com/spinwerks.htm

Personally Im one of those folks that perfer as much tire as you can run, then tune the handling with spring rate and sway bars.

This is if youre just running for fun and dont car about where youre classed.

SicMonte
10-24-2006, 12:36 PM
any 17" wheel thats not expensive as all get out....???

slowcamaro
10-24-2006, 01:15 PM
Corvette replicas can be had in the 4-500$ range, but then you'll likely need to run spacers.

If you can fit them (clear your brakes) and have nothing against it theirs alot of cheap options in 16" wheels. You should be able to find some 16x10" steel wheels on summit...they usually have a ton of backspace options....I dont think they have much of a selection of 17" steel wheels though.

6'9"Witha69
10-24-2006, 02:02 PM
If you don't mind steel then Jegs has some Cragar Soft 8 wheels in 17X8 ($53) and 17X9 ($60) sizes.

http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10002&storeId=10001&categoryId=24471&parentCategoryId=36662

If steel is out of favor, the Cragar S/S is $199 for 17X8 and $209 for 17x9

http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10002&storeId=10001&categoryId=17045&parentCategoryId=36662

SicMonte
10-24-2006, 03:07 PM
would the steel be ok for autocrossing??

SicMonte
10-24-2006, 10:22 PM
on a 9" rim....whats the biggest tire i could safelly run on that? 275?

bingham72
10-25-2006, 09:19 AM
https://www.hoosiertire.com/rrtire.htm
check out this site for tires. it's a good cheap way to get some autocross tires. If you are competing in SCCA competion, check the rule book on which ones are legal for your class.
Steel wheels are fine. I think Summit sells some cheapies 17" for $80 a piece. The draw back is weight, but unless you want to be a champion, they'll do just fine. Also you might want to go with a A3S05 tire as they'll last a lot longer than the R compounds. as for the size, Check on Hoosier's site. They have a guide on there as to the right size rim for a particular tire. Can't quite find it right now!

slowcamaro
10-25-2006, 09:48 AM
on a 9" rim....whats the biggest tire i could safelly run on that? 275?

Depends on what size rim you go with. On 16's you can get away with a wider tire do to the sidewall being taller/buldged. 9" width on a 17" rim is about as small of a rim as you want to go for 275's... Im considering mounting 275's on my 8.5's..but it isnt "reccommended"...Basically it comes down to the manufacturer, take a look at their website they usually supply a spec chart.

As mentioned above, steel wheels are fine theyre just heavy.

SicMonte
10-25-2006, 05:25 PM
im looking at a set of bogart racing wheels. They can get expensive...but they are worth it.

David Pozzi
10-25-2006, 05:48 PM
We've got 285'/17 on 9.5" rims.
with steel rims, you can probably get any width made if you search around.

slowcamaro
10-25-2006, 06:07 PM
im looking at a set of bogart racing wheels. They can get expensive...but they are worth it.

What size and style? Price? I was quoted $2370 shipped for 17x9.5's in the LS-6N road race style.

SicMonte
10-25-2006, 06:39 PM
thats exactlly the style i wanted to get...im getting a price tomorrow.

David Pozzi...what wheels do you have??

mpozzi
10-25-2006, 07:24 PM
We run Vintage Wheel Works on the '73. Check out their site as the often have "blems" that sell at a reduced price. You're looking around $1200 for a set depending on the style.

Mary Pozzi

SicMonte
10-26-2006, 10:34 AM
does it really matter that much when it comes to an autocross?? i mean they would just be on the car when im at the track.

David Pozzi
10-26-2006, 11:15 AM
Steel wheels are a bit heavier and have a little more flex, the racing steel wheels probably have less flex due to their strong centers. I'd go with steel since they are so cheap and you can easily have them cut and offset's changed or widened as you need to.
David

SicMonte
10-26-2006, 11:42 AM
cool...im gonna look into some steelies then. Most of the ones i find though require 5/8 studs...this will require some searching. and 17" steel wheels are next to extinct.

Skip Fix
10-31-2006, 11:24 AM
Look through the circle track magazine for some wheel companies. I used some custom 16x10s on my old Camaro, I want to think Bass Wheels made them? They were heavy though.They also use a 1" lug nut for the stud hole.

For another kick jump into the "prepared" classes so you can run road race slicks. John Berget sells the for cheap 1/2 tread depth. Stick like glue!