How wide can I go for rear tires on a clamshell wagon

Hello all, newbie here. I posted in the welcome forum already but need some advise. I just bought a 74 Buick Estate wagon and ordered my new wheels. 15x8 Torque Thrusts and was wondering how big of a tire will fit in the rear without having rubbing issues or having to modify anything. The offset of the wheels is 4 7/8 I was hoping to get a 275/60 or possibly a 275/50. I am going to order new BF Goodrich Radial TA's with raised white letters. Any info would be great, Thanks guys

 

My '73 has 275-60-15's on 8" rims, and there's room for more, but not much more!

 

Do you know what you are running for back spacing? Thanks

 

I'll have to look and see.

 

I bought 15x7's and bought 275/60R15's There is about one inch left to the outer lip with torque trust wheels with zero offset. I will try and get pictures posted later

 

Mine are 15x8 with +12.00mm offset (5" backspace).

 

I coould have went with 15x8's and bought bigger tires but they wanted $43 more per rim for the 15x8's It looks good enuff with the 15x7's