whats the biggest tire i can put on an 07 f150 fx4 with 20 inch rims ??

 

what size rim??

 

i feel stupid, i just noticed you said 20". Im thinking 285 or posably 295

 

285 and 295 are tire widths in mm, but I think he was asking about height.

The factory Pirelli tires on an FX4 are 275/55/20s and they are 31.91 inches tall by 10.8 inches wide. If you stick with your factory wheels, you can run a 33" tall tire without rubbing. However, if you go with a wider wheel or one with a different offset, you may have problems with rubbing.

A 285 or 295 will be wider, but the aspect ratio (second number) and rim size (third number) are also needed to determine the height of a tire.

There are lots of tire size calculators out there, so just make sure you do not go bigger than 33" and you should be good.

KR-Texas

 

I have 305/55/20's on my 07' with just a leveling kit. No rubbing at all.

 

You can run a 275/60-20 on the stock wheels without a leveling kit, and its a 33x11 tire. You can also get away with a 305/55-20 (33x12.50) but you might get a little rub on the UCA at full lock, depending on the tire you choose. You can also put on a leveling kit and run 35x12.50x20 on the stock wheels, I just did.