What size wheel is on the 01 4x4. I think it is 17"? Has anyone been able to get 15's or 16's on??

 

16" rims are base equipment with a 17 x 7.5 rim as an option. I would not recommend a rim smaller than 16" as it may create clearance problems with the disc brake calipers. Another issue with non-factory rim use is that Ford uses a metric-sized bolt circle (5 x 135mm). If it wasn't made originally with '97 - '03 F150 use in mind, it probably won't fit.