Tire sizes/Speedometer
 

Hey guys. I am looking for some advice on tires. I will be needing some new ones in a few months. I currently have Goodyear Wrangler AT/S (LT215/75R15) on the stock 15" 1998 SLT rims on the Jimmy. The car calls for P235/70R15 on the door label. What is the biggest tire I could put on this truck without having problems with the tires hitting the fender and WITHOUT a lift kit? I was looking at LT235/75R15s or larger if I can find inexpensive ones. Do they make 245/80R15s?
Also my speedometer: I noticed with the current tires on the truck that my speedometer is showing my speed 2-3 mph faster than I am actually going (confirmed with 2 different Magellan GPS' and a laptop with USB GPS sensor (NOT AT THE SAME TIME!!)). For example, if the speedometer shows I am going 65mph with the cruise control on a level road, the GPS would say I am going between 62 and 63. Thanks for any advice.

i think the biggest you can fit without a lift is 30x9.50x15. i'm not 100% sure tho.

There is a sticky in this section labeled LIFT KIT LIST. I would try looking there for some options on what size tire you can fit with what kind of modifications.

Ok I noticed something weird. A couple nights ago I picked up a brochure in a tire place. I noticed that P235/70R15 is meant for 95-02 Blazer and Jimmy and for some reason P265/70R15 is meant for the 04-05 Blazer. Can anyone shed some light on this? Aren't the 02-05 trucks the same except for the year?

For all intensive purposes, they are the same... I would take anything you read aftermarket with a grain of salt. A P265/70R15 is a 29.6" tall, 10.5" wide tire which is pretty close to a 30x10.5.

I just got a set of Goodyear Wrangler Territories 31x 10.5". They do rub slightly in a tight back-up turn and only on the driver's side front and only because of the mudflap. The 5" lift kit is on order already. The tires were on sale so I couldn't wait for the lift kit. I have noticed that at 100KPH my GPS shows 105KPH or a difference of 3.1MPH at 60MPH.