Whats the widest tire I can run on a stock rim. I have my car lowered. Its currently running 245>45>16 and with my t78 I just burn the hell out of my proxies everytime I get on it.

 

245/45 is the biggest size you should run on the stock rims. I know that for drag racing only, you can 255/60s (BFGs).

Looks like you need to move up to some wider wheels to support larger tires.

If your car is not a daily driver and never sees rain, you almost might want to consider running Toyo RA-1 or Yokohama A032R tires in the 245/45 size.

 

you would be suprise at what you can strech on a tire, in anycase, wider is not always better. Its all about tire compound. If you want grip, get slicks.

 

For a good priced regular street tire.
You can get Yokohama ES100s in 245/45/16's
A great tire for under $100 each!

 

A 265/45 16 will fit on an 8" rim .... barely. It will look like a cantilever tire. Whether or not the tire will still fit in the rear wheel well is another question. I doubt it.

 

my previous fd I had 285s on the rear with 18x10s so I dont think the wheel well will be a problem.

 

It's not the wheel well that's the problem. If you still have stock diameter springs and the stock trailing arms, I can almost guarantee that any "over-sized" fitment will not work. 2.5" ID springs are almost a requirement to fit any of the BIG tires.