Road racing and tire sizes.

**98TransAmWs-6** · 02-25-2014, 12:30 PM

I have a question about road racing and tires. For best performance is it better to have all one size tire, narrower in the front than the back, or wider up front and narrower in the back (would look weird but I have seen people do that). Basically I want a set up that can corner pretty well but wouldn't be horrible at straight-line either or I could just swap tires and be good to go. I am looking at buying new wheels and they offer them in both a 18x9.5 and 18x11 so I am debating on whether to go 18x11 all the way around or do a staggered setup. If I run the same size all the way around I would be running 315s.

**98TransAmWs-6** · 02-25-2014, 12:38 PM

Just realized I posted this in the wrong section....

**35th-ANV-SS** · 02-25-2014, 01:58 PM

I moved it for you. I really am not too up to speed on information about tires as I went the traction route and just bought Mickey Thompson ET Streets. My car cannot drive on the street with normal street tires. I've tried it, and it is stupid dangerous.

***SMWS6TA*** · 02-25-2014, 05:28 PM

I think he means for road races like autox which is better? same size all around or like drag setup, skinny's up front fat in the rear.

I've look at some youtube video's of autox and they seem to be close in size all around. Makes sense to me because those skinny's don't look like they could take a hard turn.

**98TransAmWs-6** · 02-25-2014, 05:38 PM

You are correct Scott in what I was asking. None of my tires would technically be skinnies it is just whether they are 275 in the front and 315 out back or 315 all the way around. I have heard conflicting things of what us best for road racing. I will be doing high speeds with sharp turns, obviously I won't do high speeds in the turn lol.

**35th-ANV-SS** · 02-25-2014, 06:23 PM

So your primary setup will be for autocross?

**98TransAmWs-6** · 02-25-2014, 06:35 PM

Whatever things like the Nurburgring (won't be doing that one specifically) are considered. I keep hearing that auto cross and road racing are two entirely different things as well as the same. I will be doing whatever I described is considered as my primary setup with occasional drag just to test out my quarter mile times to see how much my mods have done. When I picture auto cross I think of those cone courses in a parking lot, which may be wrong.

**35th-ANV-SS** · 02-26-2014, 01:01 PM

No, I agree. I just wanted to verify. Are you set on 18" wheels? I think they will look good and fill the wheel well nicely. I know some people stray away from larger wheels due to the added weight and additional power used to rotate them. I don't know how much of an affect this really has though.

**98TransAmWs-6** · 02-26-2014, 01:10 PM

Originally Posted by 35th-ANV-SS

No, I agree. I just wanted to verify. Are you set on 18" wheels? I think they will look good and fill the wheel well nicely. I know some people stray away from larger wheels due to the added weight and additional power used to rotate them. I don't know how much of an affect this really has though.

Not set on 18s I just found some that are around stock weight and wider for a good price. They were like 24# (18x9.5) for the front and 28# for the rear (18x11) I have recently discovered 17s will clear my calipers with minimal work. The wheels just have to clear the calipers obviously since I am running cts-v calipers and smaller than 17" will not. If I could find a decent 17" wheel in a design I like I would prefer that if it will clear my calipers with little effort since there are more tire options in the 315s for them. I have been thinking though I could get my stock wheels widened for 315s and they clear my calipers I believe but it is really tight lol. But the wheels I found would probably be the better decision since they would still be stock offset and end up cheaper in the end.

This post though is mainly about the widths for RR and what works best. I was thinking 275 in the front and 315 in the back but I don't know if that is good for RR or not. I know it would be pretty good for street and strip but I am not sure about RR. I would think so since the Z06 is set up similarly and that is really what the Z06 is best at.

**35th-ANV-SS** · 02-27-2014, 06:26 AM

I used to belong to this site back when I was in engineering...haven't frequented it in a long time, but they have a decent discussion on this if you want to read it when you have some spare time:

Automotive tire/wheel engineering - wider is better? or not? size of contact patch arguement

**98TransAmWs-6** · 02-27-2014, 08:40 AM

Originally Posted by 35th-ANV-SS

I used to belong to this site back when I was in engineering...haven't frequented it in a long time, but they have a decent discussion on this if you want to read it when you have some spare time:

Automotive tire/wheel engineering - wider is better? or not? size of contact patch arguement

Thanks I'll read up on that. I have read on various forums that essentially are talking about the same thing but I am interested to see if this forum has new points.

**35th-ANV-SS** · 02-27-2014, 10:18 AM

From what I have gathered, the type of tire and suspension set-up will likely play a bigger role in road racing than the actual width/s of the tire/s. I know there are a few people on here that dabble in road racing, so it would be nice to hear their perspective on this.

**98TransAmWs-6** · 02-27-2014, 12:21 PM

Originally Posted by 35th-ANV-SS

From what I have gathered, the type of tire and suspension set-up will likely play a bigger role in road racing than the actual width/s of the tire/s. I know there are a few people on here that dabble in road racing, so it would be nice to hear their perspective on this.

Figured as much and I know you want as much adjustability as possible which is why everything I have gotten so far is adjustable minus the shocks. I will change them out at some point for adjustable ones though after I have some rear road racing time behind me. The tire I am going to go with I think are Toyo R888s since you can still drive it on the roads but it is a competition tire as well.

I am going to search for other tires as well and see if there is a better one around the same price as the Toyo R888 as well.

**cammed goat** · 02-27-2014, 05:33 PM

For added info, look up STi Killer featured in GM High Tech Performance. Good writeup. Strip, and road racing Camaro.

**98TransAmWs-6** · 02-27-2014, 07:29 PM

Originally Posted by cammed goat

For added info, look up STi Killer featured in GM High Tech Performance. Good writeup. Strip, and road racing Camaro.

Damn I forgot about that. I want to say from memory they were running 275 in the front and 315 in the back but I could be totally wrong. I will give that a look and see.

**98TransAmWs-6** · 02-27-2014, 07:40 PM

I looked it up they were 295 in the front and 315 in the rear for the STI killer. Damn I wish I could afford weld racing RTS wheels they are awesome looking.