Does anybody know if I go to 34 Inch tires and down to 17 inch wheels will I have to get my speedometer recalibrated?

 

Please post your old tire size and your new tire size in this format:

295/70R/17

and I will tell you or use the attached Excel spreadsheet.

 

My Old tire size is P275/65R18. And My NEW size is LT305/70R17. Thanks for all your help. I really don't know what I'm doing. I bought a 2 inch leveling kit. Do you think I will need it or not? I have it all sitting in my garage waiting to be put on.

 

After the installation, your speedometer will read approx. 3 MPH slow at 60 MPH (56.92 vs. 60). This shouldn't be a big deal as Ford sets the speedometer to read 2-3 MPH (this cannot be corrected even if the new tire size is programmed into the PCM).

However, your odometer is also going to be off (approximately 5% low).

Your choice on if you want to correct it. Personally, I would when I take it in for the alignment (after installing the lift kit).

Good luck!

 

Thank you so much, I didn't even think about the odometer. I will be getting that fixed when I get it all done.

 

How much does it cost to have all of that done to fix the odo and the spedo?

 

You'd have to ask the dealer(s). Shouldn't be more than 15 minutes to hook-up to the PCM and reprogram the tire size, which probably means you will get charged for 1 hour.

 

are we sure a 17 inch rim will fit? My front rotors are very close to the 18s as is...plus some rims differ so at least check them before.

 

The guy at discount tire told me they would, even after I told him what make model etc, and after I told him about the big rotor. So I took his word for it. If the don't fit. I WILL BE SOOOOOO PISSED. I'll let everybody know either way.

 

17s will fit the xlt, stx, and xl all come with 17s standards and all the models have the same size rotors except for maybe the HD but I am not sure on that one.