JKJunkie311

Do larger tires impact the odometer and speedometer to the point that they are not accurate anymore? If so, how can that be fixed?

mpkelley20

Yes. a programmer like a Procal can be used to fix. Do a search for programmers and you will get a thousand hits on various makes/models and which ones work for each year Jeep.

Should add...if you have an auto, and don't adjust your speedo, your shift points get all screwed up too. Got to get speedo in line if you want proper shifting.

JKJunkie311

Thanks! I have a manual.

Is this something the dealership or an auto shop can do for me? Not sure it makes sense for me to buy a programmer for one time use.

Jeepztr

The Stealer-ship is going to cost you about as much as a programmer unit. You might want to read up on the subject before you make a decision.

kbp810

The dealership can/will often only program it up to whatever the largest possible stock Jeep tire is (maybe 32"?). That, and I've heard the dealership charges around $50 or more to do this; you could probably find a used procal for around $100, or a new one for around $150 (if buying used, make sure to confirm that they've reset it back to stock before sending it to you; else it won't work on your Jeep).

Either way a programmer can still be a wise investment:

1. If your jeep ever happens to get reflashed/reset by dealer, etc... you can program it again.
2. You can program again if you re-gear or change your tire size later
3. With some you can do things like set your TPMS sensors lower, or turn them off altogether (benefit that TPMS light won't go off and chime at you when aired down offroad)
4. You can read and clear DTC codes
5. With some like the diablo or superchips you can set performance tunes
6. With some you can do some other misc things like setting one touch turn signals, turning off/on daytime running lights, etc...

kh202

I wouldn't worry about it with a manual man. Just use a GPS and figure out how much your speed is off and just drive it!!

Rule18

^^I agree. This usually winds up turning into one of those "Dammit I should have just bought the ______" moments. For many people, it's money well spent. Def do your own research (ProCal, Diablo etc..). Pay attention to the features offered and whether or not all the features work for your 2013 model.

JKJunkie311

Agreed in terms of the speedometer, but what about the odometer - won't that be off too?

kh202

Yeah it is, but in your favor. Your 36,000 mile warranty will last you a few extra miles It's not that big of a difference tho. Going from 32's to 35's, mine is off by 5 percent. I'm actually going 74-75 when speedo says 70. Not hard to figure out at all.

hypeiv

pro cal is worth it for the TMPS adjustments... The OEM tire presure is like 38 or something and you are going to want to run your 35's at 28-32 so even on the road with oversized tires you are going to have the tire pressure light.

If you ever regear you will need the procal as well.