what size wheels for autocross?

Pooter · Post by **Pooter** » Fri Apr 01, 2005 11:03 pm

I am trying to build a street/autocross car and was wondering what you guys used for racing wheels, 15", 17"? What are the benifits of larger wheels? Also, do you run a rear sway bar? I have recently noticed mine causing my rear end to loose traction sooner.

thanks.
Nick

Bugorsh · Post by **Bugorsh** » Sat Apr 02, 2005 2:59 am

What type car is it (std, super, ghia? The rear sway bar should should keep the rear end flatter (less body roll) and more tire on the ground. What size/type wheels and tires are you running?? Also if you have a sway bar in back, you need one in front. If you are running a Superbeetle, you want a 3/4" swaybar in back and the front one needs to be upsized to a 7/8" to maintain the balance of the vehicle.

I'm currently running 195/60/15's in front and 205/55/16's in back. You can get different diameter rims and still maintain the outer diameter you want with different profile tires. So you can have a (for instance) 26" outer tire diameter with 15" rims and with 17" rims, the 15" tire might be a 70 series and the 17" might be a 50 series. Your tire/rim combo will determine the stagger and it is adjustable by changing one or both components.

Paul Illick · Post by **Paul Illick** » Sat Apr 02, 2005 4:05 am

For autocrossing you want the shortest and widest rim that will fit over your brakes and not bump you up into a modified class. For an A/C VW if you still have drum brakes all around that means 13" wheels, as wide as you can get them. Shorter wheels will lower your car and its center of gravity, have less unsprung weight, less rotating mass, and give you lower gearing. Taller wheels with low aspect tires are better for higher speeds and to fit over larger disc brakes.

Oh, and for bling.

Bugorsh · Post by **Bugorsh** » Sat Apr 02, 2005 9:04 am

If you have budget constrictions, you might want to determine what tires you want to run and get rims the dia. that fit the tire budget. Some diameter tires are more expensive than others, usually larger dia tire is more money, but availability of the ones you want is important too. Some smaller sizes may have a limited selction. 15" is still one of the most common sized tires avail. and are most likely to have lower prices since they are common.

If money is no object, then run whatever works best for you.

Pooter · Post by **Pooter** » Sat Apr 02, 2005 3:25 pm

Bugorsh wrote:What type car is it (std, super, ghia? The rear sway bar should should keep the rear end flatter (less body roll) and more tire on the ground. What size/type wheels and tires are you running?? Also if you have a sway bar in back, you need one in front. If you are running a Superbeetle, you want a 3/4" swaybar in back and the front one needs to be upsized to a 7/8" to maintain the balance of the vehicle.

I'm currently running 195/60/15's in front and 205/55/16's in back. You can get different diameter rims and still maintain the outer diameter you want with different profile tires. So you can have a (for instance) 26" outer tire diameter with 15" rims and with 17" rims, the 15" tire might be a 70 series and the 17" might be a 50 series. Your tire/rim combo will determine the stagger and it is adjustable by changing one or both components.

sorry, it's a 73 super. I do have the front 7/8 bar, and a tower brace also. the tires i'm running are kuhmo 711's 195/50/15-front and 205-50-15-rear.
I under stand sidewall aspect ratios, but i am wondering mostly about weight. i would assume 15's weigh less? yes, no?

ericsbracer · Post by **ericsbracer** » Sat Apr 02, 2005 9:47 pm

Depends on what kinda of 15's - Chromies aren't bad, but there not aluminum, either.

Post by **Marc** » Mon Apr 04, 2005 1:18 pm

What Paul said. You do get a shorter (which means smaller) contact patch with a smaller - O.D. tire but IMO the other benefits far outweigh that. A tire that rotates faster at the same road speed will warm up faster, and the brakes have more leverage as well. A bug with 21" (O.D.) rubber on it may look like a pregnant roller skate but beauty is as beauty does

Guest · Post by **Guest** » Tue Apr 05, 2005 12:09 pm

You will need to figure out what class you want to be in before you pick tires and rims. Most classes have strict rules for offset, size etc. and you might find yourself running in a very fast class.

R compounds are only available in a limited sizes particularly the newest and fastest. If you are allowed to run them 13? are a good call but you may have to change your gearing or get better at shifting during an event. The 13?s with R compounds and then a set of regular OD wheels and tires for the street is the hot setup.

I?m running 195 50 15 street tires. My first 3 gears are stock and my 4th is a 0.82:1 the rear end is a 3.88. Second gear works well for the autox with my 7000 (or so) redline and with the 0.82 I can still drive on the free way.