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[ExpensiveTaste]

All, I'm in the process of saving up for some Apex Arc-8's in 18x8.5 front and 18x9.5 rear. I'm going with this wheel because of weight and I need a little concavity in the rear, so don't tell me to go square. I'm trying to figure out what would make the car handle the best and I was going to go with 245/40/18 in front and 275/35/18 in the rear (Continental ExtremeContact DW), but then I looked at the weights and it would add 1 lb to each front wheel and 3lbs to each rear wheel. Would the extra width be more beneficial to an all around performance vehicle or the less weight with the stock 225/255 setup?

[ExpensiveTaste]

Nobody?

[Doyle]

Short answer: It depends.

Long answer:

There is a reason why serious racers spend a huge amount of time and $$$$ on testing tires. You've hit on a big inherint compromise: weight v. width.

Now, I could make it easy and tell you to get a stickier tire in a narrower width. But, I'm going to assume that you have ruled that out.

The ideal tire size depends on, among other things, purpose, tire compound, car weight (sprung & especially unsprung), suspension/chassis balance, power, traction needs, mechanical grip and aero grip. Now, there are obviously diminishing returns for going too far either way (wide v light). Wider tires also are subject to less deformation (assuming proper wheel width) and heat soak. Skinnier tires tend to transition better and are obviously lighter.

The only real way to know is to get a consistently fast driver in your car and keep upping the tire size until the lap times start increasing. But then that will only tell you about the ideal size for that track and driver. Now are you seeing that this is a tricky and expensive question, lol?

Do some evaluating and determine if you really need that extra width. Modern high performance street tires can already generate over 1.0g laterally with the stock sizes (see tirerack.com performance tests).

That being said, your need of "all around performance vehicle" is pretty vague, but here are my recc's depending on your definition of "all around performance vehicle":

Mostly DD/some HPDE & auto-x: change tire choice to a lighter/stickier tire like the Toyo R1R w/ 18x9.5 square and 255/35/18 or 265/35/18

Drag/Street: look at the street legal drag radials from Mickey Thompson or Nitto. You have AWD, so you don't need to go too wide.

Hardparker/spirited driving: 235/40/18 and 265/35/18

Also, get your suspension dialed in if you're interested in "handling best".

[ExpensiveTaste]

Interesting. So I'm probably more in between the spirited driving and might do some auto-x this year. Will 18x9.5's ET35 fit on the front? I don't want the tire sticking out past the fender. I'm planning on upgrading to the TCKline setup later in the year, but getting a wheel/tire setup first, as I can't stand the 32lb original wheels.

[ExpensiveTaste]

I just looked at the Toyo Proxes R1R and it actually heavier than a similar Continental ExtremeContact DW...

[Doyle]

18x9.5 fit with an et between 27 & 30 and some negative camber. Def something that would require coilovers/camber plates.

Apologies, I should have specified when I mentioned "lighter" I was comparing it to the 140-200utqg tires that most use for street/track duty. The R1R's tend to be between 1-3#/tire lighter than the others (I'm using 255/35/18 as my metric). Those tires tend to have stiffer sidewalls, and thus are a bit heavier than the 250+utqg tires.

[ExpensiveTaste]

Originally Posted by Doyle

18x9.5 fit with an et between 27 & 30 and some negative camber. Def something that would require coilovers/camber plates.

Apologies, I should have specified when I mentioned "lighter" I was comparing it to the 140-200utqg tires that most use for street/track duty. The R1R's tend to be between 1-3#/tire lighter than the others (I'm using 255/35/18 as my metric). Those tires tend to have stiffer sidewalls, and thus are a bit heavier than the 250+utqg tires.

If you don't mind me asking, what's your setup? e90 or e92? LCI or pre?

[Doyle]

Right now I am on winters. This spring it'll likely be: e90 pre-lci xi, TC Klines w/ -2.5 to -2.8 camber, 18x9.5 et 30, 255/35, and whatever fender massaging/trimming that needs to happen. Shop measured and it'll fit (as confirmed by other drivers on these forums).

From there I'll experiment to see if I can squeeze 275s up front. With the -2.5 camber I'm running up front there is tons of room. I ran 245/45/17 during the summer and could almost fit my fist in there (that's what she said...).