staggered tire size ??
 

2012 gt brembo, have 255 40 19 front 275 40 19 rear, the fronts are 27 in. diameter and rears are 27.7 i believe,275 35;s are i like 26.4 or 5. Would i be better off going to the 275 35 because its closer to the diameter of the fronts??? The reason i went staggered in the first place was because i dont care about rotating tires (the rears for some reason dont last that long.lol)and i wanted a little more understeer dialed in. input appreciated!

There are few other considerations to the 275/35 vs 275/40 discussion

1) 40 sidewall offers a bit more flax, which may be helpful getting off the line plus it makes for a softer ride.
2) 26.7" tires (275/35) will be ever so slightly easier to spin, and may give you a bit more aceleration at speed due to lower radius and rotational mass.
3) This change will make the rear of your car drop about 0.5", which will likely get rid of rake. Not sure if you like the rake look, but that's a personal choice.

guess i,m just going to go front and rear springs,either SR,Steeda or BMR sp009,they should work well with the koni str;t and gt500 mounts will give me a 1.5 inch drop. Steeda sprt springs good for an everyday driver and the koni orange and will they give me at least a 1.5 inch drop?

I have the Steeda sports with Koni Oranges on my 2011. Great feel and not to harsh on the street. Steeda says they give a 1.5 drop in the front but I didn't take before and after measurements to confirm. It is noticeably lower in the front after the spring swap.

Actually Steeda Sports drop 1" front and 1.25" rear... at least on 13-14 GT cars.

Yup, that's how much mine dropped with the same setup on the same optioned car!

I don't know what I was thinking, you guys are right. The Steeda sports drop 1" in the front and 1 1/4" in the rear. Either way they were a good match with the Koni Oranges. Thanks for catching my mistake.

How about 285/35? Same set up as the Boss and it's really close to the 255/40 in height.

285/35 would be perfect but on the stock brembo wheels 19X9 its a bit of a stretch i think! Anybody running a 285 35 on them??

All the tires I have seen recommend at least a 9 1/2 wide wheel for the 285's. 275 is the widest recommended tire for the 19 x 9 rim.

yup. You can do it, but there will be more flex of the sidewalk since the angle won't be right. I wouldn't recommend going wider than 275