I own a 2010 ST/SXT with 265/70R17 tires and I'm interested in putting on 09 Sport rims 275/60R20. There is a little over 4% difference in circumference. What are the benefits or disadvantages to changing? I like the fact that they are Mopar and match well but don't understand why the difference in essentially the same truck. Can the computer be reprogramed to compensate for the difference? Any suggestions would be appreciated.

 

Only thing I can think of is that when my father put the Mopar 20's on his truck they didn't have those stupid tire pressure gauges in them so the light was ALWAYS on on the dash...

 

Off road performance is better with the 17 inch tires IMO. This is especially true on rocks where sidewall flex is beneficial. You will also be hurting your low end performance because you will be raising your final gearing. The 3.55 is an open diff. I wonder why an open diff. on a 4x4? Even with TC, that doesn't make sense to me. Make sure and keep your TPS.

 

You can tow less

 

I've heard the same.. that you can haul more with 17s. Any idea what the gearing difference would be. Also, if this is a permanent change, I'm curious if the computer could be programed so it reflects the proper size tire. I'm assuming that is the only difference between these trucks.

 

JB007 do you know if your father could have the sensor installed when or if he gets new tires does it have to be mopar or could it be something from a tire store?

 

You have to use the Mopar sensors for the air if that what you are talking about. That is what I was told by a dealer and a tire sales person.

 

The first '09 I had came with 17's. I picked up a set of factory 20's. The speedo was not off by much according to my Garmin - when it indicated 65, I was actually going 67. I wouldn't worry about that. If you end up with a programmer, they let you adjust for tire size. I still have those original 17's in my garage - I let the 20's go when I traded that truck in 5 months later.

 

From what I've read from other posts, there doesn't seem to be much difference swapping these. But I'm wondering if the dealer will reprogram the computer for warranty purposes.

 

talked to my buddy and he's undecided still about swapping my 17's for his '08 20's he talked to a dealer and the dealer said that the 08 and the 09 rims are off by 1mm so 3 lugs will fit the 4th is off and the 5th would be way off. but yet when you get on to a wheel website the lug pattern for both are the same, what gives? the dealer trying to make a dollar or what... as for the sensors do i buy them from the dealer then take them to a tire store and have them put them on or do i have to now get tires at the dealership if thats the case forget the 20's i need my truck here not waiting for a day to put tires on at the dealership.