I just bought 20x8.5 and 20x10s boss 338.

What size tires should I run? I might be off or whatever. But I was Thinking...

Rears 295/35/20s
Fronts 255/45/20s

Anyone have any advice? Or different sizes I should look into?

 

Your proposed front tires are an inch taller than the rears. 255/45-20s are 29" tall, 295/35-20s are 28". ASSUMING you have selected the correct offset on these wheels, the rears will be fine. The fronts, in addition to making the car look like a 1950s tail dragger, will rub. I'd shoot for something in the 27.5" diameter. If you can get 245/40-20, those would be about right.

 

20x10 6.2" backspacing
20x8.5 5.2" backspacing

 

That's about 1" positive offset on the rears and about 0.75" positive offset on the fronts. That puts your tires closer to the inboard side. Don't know if this is an issue or not.

 

Should I look into spacers?

 

You can always get them if you need them. Try the wheels without them first.

 

True.