Running the stock 15's - CEG Archives

Not with race tires or any other good performance street tire. The sidewalls are so stiff on those tires that they make up for it. Plus having more sidewall is good, to a limit, for autoxing. Basically it allows you to have the ability to adjust tire pressures to match what is going on with the car. The shorter the sidewall the less the tire pressure actually makes a difference. It is almost always true to run the smallest wheel you have at your disposal that will fit.

Another advantage to 15's is cheaper tires.

The best rim size is the smallest that fits over the brake rotors. I'd stick with 15" rims even when you get 17" later. Sell the 16's as you say they are heavier. If you have tires already for the 15" rims, great. If not or when it comes time to replace, Falkin Azenis Sport is what you want if you want to stay in street tire class. They are cheap and great for dry grip.

Yeah, the 16's about a pound or so heavier, but it's also 1" wider... It's 16x7.5" instead of 15x6.5". When I can afford 17's for street use, I'll most likely use the 16's for AutoX and winter, and the 15's for dragstrip and spare.

Originally posted by AirKnight:
Yeah, the 16's about a pound or so heavier, but it's also 1" wider... It's 16x7.5" instead of 15x6.5". When I can afford 17's for street use, I'll most likely use the 16's for AutoX and winter, and the 15's for dragstrip and spare.

I'm telling you, forget the 16's! Use the 15's to autox, talk to any experienced autoxer and they'll tell you the same thing. If the wheel fits over the brakes and is wide enough to get the tire you want on it, don't go bigger! I'm not against having 17's on the street, but I race with the smallest, lightest wheels I can.

Rim diameter has nothing to do with how the car handles, remember tires do the handling. So there is never a need to take performance away by having larger wheels.

Originally posted by 5speedSE170HP:
what do the RE71's look like? are those directional? i couldnt seem to find them on tirerack.com.

Since you asked about RE71's....here's what they look like.

This is a brand new RE71, and yes they are unidirectional.

<whisper>...I have a single new one 205/55VR15 (in the pic) that I'd part with...

- Kerry

Those look a lot like BFG KDW's. If they have handling close the BFG's you'll be really happy for a street tire!

Originally posted by kerrychin:

Originally posted by 5speedSE170HP:
what do the RE71's look like? are those directional? i couldnt seem to find them on tirerack.com.

Since you asked about RE71's....here's what they look like.

This is a brand new RE71, and yes they are unidirectional.

<whisper>...I have a single new one 205/55VR15 (in the pic) that I'd part with...

- Kerry

thanks for the pic. im set on tires for now. i think ill be gettin michelin pilots again after these. the ride quality was a lot better with the michelins, the good thing about the potenzas is that they're cheap.

You're welcome for the pic.

RE71s are OLD technology. Used to be on the 2nd-to-last gen RX7s. Apparently only good in the wet when brand new. I think they were primarily used on early 90s Japanese sports cars.

Treadwear is 180 I think!

Kerry

A wider rim can get a much wider tire, though. But I think the 15's are still the way to go, and cheaper tires too.

Originally posted by APT CSVT:
A wider rim can get a much wider tire, though. But I think the 15's are still the way to go, and cheaper tires too.

This is true, but can you get much wider then a 225 under the fenders of a Contour? You can get 225's on a 6" rim (well race rubber anyway, I wouldn't put street rubber on that narrow of a wheel). This coming race year I intend on trying to put some 245's up front, we'll see how that goes.

225's is the max you can put on without rubbing. But see, the optimal rim width is when the rim width is 90% of the tire width. When I put my 225/50/15 on the stock wheels, the tires are about 75-80% of the wheel rim width and that's the minimum... This season I can't afford 17's, so I'll be using the 15's for racing, and 16's for street. Thought next year, I'll be using the 16's for AutoX, 15's for dragstrip, and 17's for the street.

Originally posted by AirKnight:
225's is the max you can put on without rubbing. But see, the optimal rim width is when the rim width is 90% of the tire width. When I put my 225/50/15 on the stock wheels, the tires are about 75-80% of the wheel rim width and that's the minimum... This season I can't afford 17's, so I'll be using the 15's for racing, and 16's for street. Thought next year, I'll be using the 16's for AutoX, 15's for dragstrip, and 17's for the street.

With race tires I don't believe you have to follow that rule. I'm going to use some spacers to try and squeeze the 245's on the car. A little rubbing will probably occur, but it will be for a very short duration.

If you look at the rear strut and rear tire, you'll know that not even 235 is possible... I have 225's on for Summers, and I can barely slip my finger in between the gap of the tire and strut. Anything wider will rub constantly. The front ones might have a little more lee-way, but I doubt it.

245's aren't for the rears...as stated above only for the front. Instead of adding a bigger rear bar (which isn't legal for stock) and making the rear end grip less, I'm going the opposite direction and making the front end grip more. I believe with the right spacer dimensions you can get 245's on the front. I have victoracer 225/50's on the front with no spacers now and they rub only during long hard sweepers. I think with a 1/8 spacer I can get a little bit more out of the front.

Originally posted by AirKnight:
225's is the max you can put on without rubbing.

doesnt Rick have 235s?

Originally posted by Qbert:
245's aren't for the rears...as stated above only for the front. Instead of adding a bigger rear bar (which isn't legal for stock) and making the rear end grip less, I'm going the opposite direction and making the front end grip more. I believe with the right spacer dimensions you can get 245's on the front. I have victoracer 225/50's on the front with no spacers now and they rub only during long hard sweepers. I think with a 1/8 spacer I can get a little bit more out of the front.

What class are you going to be running in? Unless you're in mod classes, the max tire width is 225. And actually, for stock classes, changing the tire sizes are not allowed. Just nobody pay too much attention to it. But if you stick 245 on the Contour, people's gonna notice.

Originally posted by AirKnight:

Originally posted by Qbert:
245's aren't for the rears...as stated above only for the front. Instead of adding a bigger rear bar (which isn't legal for stock) and making the rear end grip less, I'm going the opposite direction and making the front end grip more. I believe with the right spacer dimensions you can get 245's on the front. I have victoracer 225/50's on the front with no spacers now and they rub only during long hard sweepers. I think with a 1/8 spacer I can get a little bit more out of the front.

What class are you going to be running in? Unless you're in mod classes, the max tire width is 225. And actually, for stock classes, changing the tire sizes are not allowed. Just nobody pay too much attention to it. But if you stick 245 on the Contour, people's gonna notice.

??? What stock class are you running in? Tire size can be changed all you want, wheel size cannont. I plan on taking my car to Nationals this coming year in GS. I realize I don't have a prayer, but I only run about .5 seconds off of the pace of the guy that took 8th place in GS this year. Hopefully I can afford Konis this year and that should give me the .5seconds. Don't take me for someone who only shows up to 1 or 2 autoxes a year. Feel free to run your 16's, but the first time a good driver shows up you're going to be wishing you put the money into driving schools wrather then tires and wheels.

http://www.moutons.org/sccasolo/Rules/street_touring.html#17.3.%20TIRES

That is for Street Touring which allow some modifications (ie. basic bolt-ons) done to a car. It says 225 is the maximum tire width.

Please don't lecture me about driving school. I know very well driving school is the best thing for the racing. And by the way, .5 seconds is quite a bit of a difference when you're at national level. And for your comments about my wheels/tires, no I'm not putting extra money for them. I'm going to be spending the extra money on the 17's for the street already, and the 16's will just be sitting here collecting dust that's why I'm going to be using them for autox.

Originally posted by AirKnight:
http://www.moutons.org/sccasolo/Rules/street_touring.html#17.3.%20TIRES

That is for Street Touring which allow some modifications (ie. basic bolt-ons) done to a car. It says 225 is the maximum tire width.

Please don't lecture me about driving school. I know very well driving school is the best thing for the racing. And by the way, .5 seconds is quite a bit of a difference when you're at national level. And for your comments about my wheels/tires, no I'm not putting extra money for them. I'm going to be spending the extra money on the 17's for the street already, and the 16's will just be sitting here collecting dust that's why I'm going to be using them for autox.

Yes 225's are the max in STS along with a 7" wheel or a 7.5 (can't remember). I run GS though which allows any size tire you like.

Yes .5 seconds is alot, but when you concider I had a stock air filter, shocks, and exhaust. I also do not have an alignment that is worth a crap on the car. The only thing I did have was race tires (which is obviously the biggest factor).

My comment was meant about tires...you'll spend more on your 16" tires then you will with 15's. You make more power with the 15's, you can get just as wide of tire on them, they weigh less, they are cheaper, what is it that you gain from running 16's?

If you plan on running your 3L you need to be in Street Mod. Which you can run any size tire you like and it better be a DOT race tire if you plan on standing any sort of a chance (unless the locals are running street tires). If you're just out to have fun then it doesn't matter what you do just have fun.

Yeah, but that's what happens when you run stock class, everything is basically stock.

I'm going to be running the 16" tires that I'm going to be running on the street this summer (using them the year after for just racing). And those are going to be Bridgestone Potenza RE730 Gen II or S-03 Pole Position. And I'll be in street mod, but I'm not worried about winning because I'm not good like that yet.

Rick has 245/45R16 on a 7.5" wide rim IIRC. He uses a spacer.