Fuzzy_Wuzzy

iTrader: (8)

I can't say that I have tried much else, but The V12s are a great tire for the price. I would love to go more aggressive, but but 12x autocross sessions in a year I'm buying tires every year, I can't see a few hundred dollars a year more entertainment. Plus they work good. With 12x autocrosses (9 runs each) i got about 1 year and 4000 miles on the tires. The set before that about 11000 with the same amount of autocross. (so drive all you want in a year when autocrossing, it won't make much difference in your tire wear) We will see how long this current set last.

LAYGO

iTrader: (10)

255/40/18 all the way around is 2.4% too fast per tire tool. That's no big deal, right? It's when it's a difference between front to rear?

Or is it just it has to be less x% than from stock?

I need to order ASAP.

Dmax/04V

You can always adjust your ecm for tire/wheel size using EFI live, or HP tuners, as long as the rear wheels have the right tire/wheel size in the ecm your speedo will show correct.

mikeam

I put on a set of Conti DWs, stock size, 2 weeks ago. Much more grip on wet or dry pavement than the stock GY RS runflats (28K miles out of them).

Mike
NC
-2007 CTS-V, 100% stock. 28K miles
-2000 Vette convertible, Original Owner, 39K
-2006 Tacoma, 50K

JDB

iTrader: (2)

Which Continental ContiSport? If you want 275/40/18 in rears, only summer tires in that size are the Contact 3 SSR at about $400 each and a runflat. If you meant Continental ExtremeContact DWS, then its a step down to an Ultra High performance category as well as an AllSeason tire which you may need in NJ if you ever get caught in "not really the snow".

Personally, I don't understand the want for 275 rears when you cant increase the fronts to match. ...since you're adding more rear grip that means you're increasing understeer. Maybe that doesn't matter to you, but it does to me when I use summers as a track (road course, not the strip) setup.

You mention 25k miles a year, so I assume wear mileage is a concern.

Unfortunately, it sounds like you'll need to compromise something. Or, do what I do... 3 sets of wheels and tires. ...Blizzaks now (Nov-April), various summers that I justify spending more $ on because they only see ~6 months use on the street and occasionally track, Nitto NT01 track if dry and want more grip than current summers.

You have to pay to play, or compromise something.

JayBirdWs6

iTrader: (1)

H&R springs with MM Spacers in the rear is my setup. So 255/40-18 all around I should be good I just need to correct my ecm?

54inches

iTrader: (4)

It has nothing to do with front to rear unless you are AWD or 4WD.

It is about where your torque, speed, etc are compared to the stock set of parameters.

Generally, The taller the tire, the less performance you are going to get out of the car as it makes the car feel like it has lower numerical gears. Same is true for much shorter tires; theoretically gives you greater performance under certain conditions, but could lower your top end speed.

In actuality, 3% is nothing and just a parameter that one tire size calculator has set. I am not sure what they are basing that value on, being good/bad, but it is their parameter.

Hell, it could be just that that person programming the calculator did not want their speedometer to be off more than 3%. I don't have that answer.

Case in point:

3% of a 27" tall tire = .81" or basically 13/16"
3% of a 40" tall tire = 1.2" or basically 1 1/4"

Onefast V

iTrader: (3)

People main concern is different tire diameters front and rear can affect the stability control system because they will have different effective rotational speeds (RPMs). I have not had a issue running 245/45 up front and 275/45 in the rear (speeds up to 130mph on the track) but others have had different experiences

LAYGO

iTrader: (10)

This.

This is what I remember, but I couldn't when I asked. As long as front/back have roughly the same height (rotational speeds being nearly the same), it won't throw the stability errors. But being all together different heights from stock is irrelevant (sans speedo correctness), so long as they're close in height to each other, front to rear.

54inches

iTrader: (4)

Never thought about that as well. Great point!