Hey guys...I had some 305/55/20 Terra Grappler AT's put on my stock 20" wheels earlier today...I drove it home and found that my upper a arm ball joint is dangerously close to the inside of the tire!! Dangerously close as in, I can get my index finger in between, but only up to the first joint....Is this too close??? I just feel like its going to flex on bumps in the road and scrape the tire!

The truck is a 04' FX4 Supercrew with a 2"spacer up front...thats it!

 

I have some 12.5 wide tires on my stock 17s. The distance btwn the tire and ball joint on mine is about the same as you're describing(maybe a hair more). Either way I have never had mine rub or even come close. Besides you would have to do some serious cornering to flex the tire on top that far, most of your flex is on the bottom where it meets the road and the lateral forces are. Also with the proper inflation they won't flex much either and with your 20" rim you have a short sidewall than I do, so will get even less flex than me with the 17.

 

Thats kinda what I was thinking...I was just worried that with it straight forward and hit a good bump if it would have enough force to drive into the sidewall of the tire and cause catastrophic damage???!!!!!!!

 

You have plenty of room. The only way it will touch is if you have an accident or something. My 22's are the same way. Last year, my wife had an accident with a deer. The deer ran into the corner of the Expy and hit the wheel. There was a rub mark on the tire and upper control arm where it actually knocked the wheel over.