I'm preparing to put 35" s on my 2013 rubicon unlimited. I know the speedo will read wrong... But is it important and if worth it to get a programmer and change computer settings?

 

Yes if you have an automatic. It will still drive but the shift points will be off. This will affect mileage and overall performance. Also may want to consider the stability control. Maybe someone more knowledgeable will weigh in on this aspect. In a straight line it would be ok but different diameters than what the computer thinks is there may affect it in cornering. I know people run them all the time without changing it but doesn't make it the best choice. If all you want is a tool to reprogram a speedometer, they can be relatively affordable.

 

Yeah it's not the price of the tool to do it ( obviously a drop in the bucket compared to all the other mods) more the fact I am unsure how critical or not it is. I'm leaning towards doing it , but figured others experience would be great.

 

I just put 35's on our 2013 JKUR and used a flashcal to set the computer for the new tire size. I cant say what it would have been like to drive without resetting the computer as I did the adjustment before taking it out for a drive, but I can say Im happy with the shift points and the speedo is dead on after reprogramming.

droidage.....

 

Definitely do it, you'll be much happier with it.

 

I admittedly cant comment on what it's like after, but I'll got the other way. I've got an 07 that was on 35's for 2 years and 37s now for about a year and I just don't see the point. It drives fine and has no effect on road manners.

 

If it isn't a money issue, I'm curious what the reasoning is for choosing not to correct? You want your passengers to think you are going slower than you actually are? Better trade-in value from the mileage reading 99,000 instead of the actual 100,000 ?

 

Ha ha ha , no. Jeeps hold their value just fine without the small mileage gain I'd get. More of a " is it really necessary" question. Rest assured. I ordered the tool this afternoon. When I mount the tires, I'll update the computer as well. Thanx again for your opinions people I appreciate it!

 

What would you use for this? Aev procal? Superchip?

 

I have the superchip just for the screen and other programmable features. I think they will both do the same job.

Absolutely necessary? No. I went from OEM 30's to 33's on my auto tranny TJU with 3.73 gears. I was disappointed and felt that it was more sluggish than I expected. Swapped the Speedo gear and it made a considerable difference in the shift points and I was adding 10% extra mileage on the odometer. Guys with manuals choose their shit points anyway so it is only an issue with the odometer. IMHO I consider it necessary for my vehicle.