18" Tire Size Options

[WallaceMFG]

Looking for tire size options for our 69 Chevelle. Currently has 275/35R18 tires on all four corners on 18" x 9.5" wheels. We are looking to step up the rear tire size a bit, wanting to see what the next common size is for 18" tires. We originally picked the 275/35R18 because there were lots of options available, but the car could use more rear grip. Stock tubs on the rear, but still have plenty of room to play with.Thanks for any input!

[68Formula]

How much extra? Not much in 305s. A 315/30R18 has some selection. 295/35s are a little more limited than the 315s, and 295/30s are too short.

Once you go larger than 285s, then you seriously need to consider going wider on the rim to really reap the benefits for lateral grip.

Actually, were you considering more straight-line, or lateral grip? If you mean lateral you could tune the oversteer with stiffer springs or swaybar.