Got a 99 F150. OEM tire size is a 255/70r16. Was wondering if I could run 235/70r16's in the front and the OEM tire size in the rear. Or if it would even be safe to do so.

 

If you drive a 2wd, yes.

If you drive a 4x4, yes if you never engage the 4x4 system.
You can damage 4x4 system if you use 4x4 with different tire sizes on different axles.
What is the reason for the different sizes? Worn out tires and you can get a pair of 235's to get you through until you can get new full set?


Note: The 235 tire option is about an inch smaller diameter than the 255 option.

 

Yeah just using 235's as a cheap option right now until I can afford new 255's or possibly 17 inch tires

 

As a temporary solution as described above it's OK, but far from ideal. I'd much prefer to have all tires the same size and type with the same number of miles on all them. But sometimes you gotta do what you've gotta do.

 

Unless you just have them, you’d spend more money in the long run that way.