Hi, I have a 1988 4 runner with a 4 cylinder engine ( not sure of the rear end gear ratio) and need to replace the tires. I am undecided on the size. I have 15" rims. Would 225/75R15 or 235/75R15 be best or should I go with 31's?

 

I prefer the 31 inch tires. I think they look and ride better and am almost positive it gives a 1/2 to mile more to the gallon of gas. It can throw your speedometer of by 5 miles or less but is well worth it to me. I tried a set of factory size tires one time and it did not take me long to regret that decision. On my runners and truck, it is 31 from here on out. The factory size just looks like donuts to me on them. To me the 31 has much more give and flex for a smoother ride.

 

X2 what Terry said. 31's can be run with stock gears.

 

31's all day, baby. Cruise speed is better, mileage is kind of a wash. Do it.