gleninsandiego

I am still wrestling with tire size and fitment for my 73 for performance street and autocross

1. Will there be a big difference in handling performance between the 255/60/15's and the 245/60/15's?

2. If there is, will it also handle better with 255s in the back and 245s up front instead of 245's all around?

3 Would the same be true if I went to 17's?

Glenn in San Diego

gleninsandiego

anyone?

LT1driver

can't answer your question but I used to visit a girl named peasley in your town when I lived in san berdo I had 255/60/15 on 73 once and didn't see any real or noticeable difference over a 70 series tire.

The Money Pit

I've run both sizes and can't say there's any difference noticable. Right now I run P 245 60-15's on the front,P 295 50 15's on the rear just for the stance. They're 1/10 " different in diameter,so as close to level as I could get,which is what I wanted.

If I were to advise mixing sizes,I would think the P255's in the back would aid in handling some.The rear's lighter,and the extra traction may help from coming around in the hard turns. This was my thinking when I swapped the P 295 50's on mine.

That and the 540 horse 406 needed the traction.

jim2527

No difference. Keep in mind 255 and 245 are sidewall width and having nothing to do with tread width. Depending on manufacturer a 245 could have more tread width than a 255.

Roughrider

Tread compound has as much as anything to do with handling. A stickier tire will do better than a different brand in the same size with a hard compound. Wider tires on the front can be a mixed blessing...maybe better grip but increased steering effort. That may or may not pay off on the track.

With 17" tires, you have a far better selection of tires with great handling characteristics. The 15" has more or less been left behind when it comes to the best technology. Hell...even my daughter's Kia Spectra has 16" tires on it.

Regardless of what size you decide on, get the stickier tire (go by its traction rating on the sidewall), then experiment with what tire pressures give the better handling.

auctionman256

try 225 70 15r

spike1360

Don't mean to second guess as I know very little on the matter, but isn't 255/45 the number of mms across the tread of the tire and the 60/70 is the percentage thickness the sidewall is compared to the top wall?

rihwoods

Shave them Glenn...get more grip....

OzzyTom

Roughrider said it....

Tyre compound is more important for adhesion/handling rather than size.

Not to mention wider tyres are more prone to aquaplane in the wet if used as a street car.

17" tyres give you greater selection for better quality rubber.
A thinner cross section (eg 45 series) will also improve handling but reduce ride comfort.
I'd be going for 17's or even 18's if road racing / autocross is your plan.
With 18's you'll also be able to fit larger rotors/brakes when you really start to get serious.

weimer20

That's not second guessing. That's correcting an error.

wiseman79

No, he's correct. Tread width is another measurement, 245, 255, etc measures the width of the tire at the sidewall or the buldge.

Here's a quote from Tirerack since I wanted to remove doubt...

"The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width."

gkull

You can not use the word performance and 15 inch street tires in the same sentence! 17 inch actually have tires rated a AA traction and A temperature. The shorter sidewalls actually raise the cornering "G" force. My street fronts are 255/45/17 they actually hold pretty good.

73jst4fun

Had both both sizes you have mentioned on my 73 and didn't notice any difference in a 60 series 15" tire and were not considered performance tires, just speed rated. I now have 16"/front and 17" in the rear both are 50 series tires now and there is a big difference in handling due to the shorter/less flexing sidewall and the rubber compound of the performance rated tires....I would go with 17" or 18" tires with a better selection however it's tough keeping existing tire height the same along with gearing and clearence issues if you want to go big.

rihwoods

Glenn...are you going in stock class or improved stock ??? I'd look over rules/classes,then go from there....also,auto X at Qualcomm is not the "high" speed it use to be...mostly second gear now...so your stock brakes are fine....it all comes down to suspension/tires....I was the only C3 out out there in 2006...competition is tough...got my azz handed to me...but it was fun...

It is not like the early 80's when we ran against other C3's and Porche 911's...
2006..


Here is vid from 2007 at Qualcomm..99 Miata...your competition.

http://www.youtube.com/watch?v=2NDVgjj1wAA

gleninsandiego

Rich

As silly as this might sound, it doesn't matter what class I am running. I am primarily doing it to have fun with my family and friends that are more competitive. As you said, I get my you know what handed to me on a platter when I do it. Last year I was running a 1972 Capri, the car of my youth, which was totally uncompetitive but a lot of fun being old school.

I sold the Capri and got the car I really wanted back then, the 73 Vette

What was fun for me was watching the 90 C4 that I sold a few years back win last year National Tour in its class and the Pro Solos as well. This year the next owner won her class in the National Tour with it.





Glenn

Dashcam NYC

Are you kidding me? The first set of numbers are WIDTH of the TIRE. WTF is a tread width?

resdoggie

Your responding to an 11 year old thread.

Hostred12

There can be a significant difference in handling performance between different tire sizes, so it really depends on what you're looking for in terms of handling. If you're looking for more grip and better handling overall, then going with bigger tires (255/60/15's) would be the way to go. However, if you're just looking for a bit more grip and not necessarily the best handling, then going with smaller tires (245/60/15's) might be a better option. Ultimately, it really depends on your specific goals and needs.

scottyp99

This was posted 3 years ago, so.....14 year old thread?

Scotty