07RubiJK

why not just use a GPS to determine your true MPH and leave it. In the end, you'll put less miles on your odometer. That's what I have always done, if you know your 6 over at 55, just compensate. I just keep my GPS in the Jeep and go by it vs the speedo and put less miles on my odometer, which could help if you ever resell. JMO.

mbrown2

I am interested in this as well....how are the shift points determined? RPM or Speedo?

Tom07JK

Superlift says as of now that the tru-speed isn't supported for the 2007 JKs. That just means they haven't tried it. I would bet that this will be the way to go. I personally want my speedo to be as accurate as possible. There are so many electronics that rely on that info that it really can affect your driveability. This will make a difference more on automatics than the 6-speed models. The tru-speed adjusts the signal from the speed sensor and tricks the computer this allows you to adjust your speedo regardless of the factory computer settings/tire size/ or gearing. Truspeeds can be had for around $200. That is about double what your dealer will charge to change your calibration to one of the available factory tire sizes.

Later,

Super Jeep

Had mine flashed yesterday at the dealer for 19.95 to a 255x75x17. Which makes it closer than the 16's that came on the jeep. The shifting seems to be close to what I can live with now. Not sure about the speedo as I have not had anyone pace me yet but I was 7MPH off when I first lifted it.

clubber

Maybe i'm uninformed, but the shifting is affected with a larger tire ? I'm going from a 32" to a 33" . I it nessarry to get it flashed ?

Tom07JK

Only on an automatic.... I doubt that changing from 32" to 33" would make much difference, but 32" to 35" would.

Later-

sgt rock

with 37 in tires i am now seeing 13.9 miles a gallon!the only thing i could do is try to do an estimation from how many miles i drive and how many gallons i fill it up with. navigaion system shows me running off.....if the odometer shows 50 the navigaition shows 60....

the rockster

TwinsJeep

I'm curious if anyone has had this done yet. Eddie posted a link on the project-JK thread to a pdf brochure with the new MOPAR JK accessories; among them is a 35" spare-tire carrier.

So tell me, if MOPAR is making accessories to accommodate larger than stock tires, why haven't they developed technology upgrades yet so that the hardware can talk to the software?

It seems to fly in the face of the advice (allegedly) given to one of the members here by Jeep (there's a post in this thread) that Jeep does not recommend upsizing the tires.

Comments?

Woods

This is Mopar. They are only talking about a 35" spare. Last I checked the computer flash does not effect the spare.

Bad joke, I know. But someone had to do it.

I'm actually with ya brutha. But I think the argument is a bit of a stretch.

I'll shut up now.

jeepingib

The problem is in the legalities the way I see it. Putting larger tires on it affects the way that a vehicle drives and reacts. It makes it stop slower for one. This can be considered a safety issue, so I doubt that the lawyers will let them develop software to work with something that they might be sued for later.