I have a 04 supercrew FX4 with I think 18x8? rims with the stock 275/65/R18 tires. I was wondering if it was possible (due to the brake clearences) to downgrade to a 17 inch rim, and run some larger tires. Here is what I was looking at

Im not even sure if 315/70/r17's are even bigger. Are there any pros or cons to downgrading rim size. I don't want to make it look bad. I just figured smaller rims would mean cheaper and more plentiful tires choices. Thanks in advance.

 

Your OEM wheels are 18x7.5. Since you have an 04, you can go down to a 17 inch wheel. Ford changed brake calipers during the 05 model year causing fitment issues with some aftermarket 17 inch wheels. The 315/70-17's are approximately a 35x12.50-17 tire. You will need to install at least a 2.5 inch leveling kit to fit 35's. Also, they will fit easily with a leveling kit and OEM Ford wheels, but the backspacing and width will have to be perfect to fit with an aftermarket wheel. Your stock tires are basically a 33x11.00-18. Really, there are as many off road 18 inch tires as 17's.

 

Thank you very much, you have been very helpful.