Changing Tire Size

Hello, I am new to the forum and am looking for some information on my truck. I have a 98 Ext. Cab 4X4 with the 3.4 V-6. When I bought it use it had the TRD bigger Alloy rims on it, but small tires. If I go to 31's like the TRD had will I need to change anything to keep the speedometer/odometer accurate? Also what kind of hit should I look at for gas mileage? Thanks for any help.
Kurt

 

look on the drivers door jam that will thell you what size the truck should have anything else will change your speedometer at most 2mph

 

Thank you for the help. Is there a way to get it adjusted so that it would be correct? Thanks again.

Kurt

 

yes there is there is a programer i think skyjacker makes it is around 200.00

 

Thanks again for your help.

 

I decided to go with the 31's, but am also looking at possibly going with 8" wide rims instead of the 7's. I am looking at the Pro Comp Alloys #1069, it is a 15x8 with a 3.75" back spacing. Or the American Racing Outlaw II #62 in a 15x8 also with a 3.75" back spacing. My truck is still at the stock ride height, will I have any clearance issues with the 31's and either of these rims? Also does anyone have these rims that I could see a picture of them on a truck? Thank you.

 

you should have no problem, the 8 inch rims will cause the tires to stick out a bit though.

 

Thank you.