315's and Speedo Recalibrate

[JEly]

Just installed the 315's I bought from Sams and I am wondering if anyone knows the number I need to have my speedo recalibrated? I thought someone said it was 601 or 606 but I am not for sure.



Thanks

JIM

 

[Bunn]

According to a thread a while back it is 601.

 

[RCoelho]

I got my 3152 installed yesterday and was wondering how exactly do you recalibrate the speedo? Is it a dealer thing

 

[David Muench]

Take it to the dealer, and they can reprogram the computer with their scan tool. It's under the ABS system, you need to reprogram it for 601 revs/mile. They'll probably charge you a half hour labor or something.

 

[klenger]

That is so cool that they can do that electronically now. Sure beats changing gears in the spedo pickup sensor. Also, if you can set it to within 1 rev/mile, you should be able to tweek it really close, even with stock tires.

 

[Tejasdge]

When I had mine re-calibrated by the dealer, they said that 636 revs per mile, if I recall correctly, was the closest they could get to 601. I'm now off by 5% verified by mileposts and GPS. While my warranty will last 5% longer I would rather have it correct. Seems like the ABS isn't happy with the difference, and wants to lock up instead of modulating the brakes when you really stomp the whoa pedal. Is my dealer full of it or is that as far as you can recalibrate with the 4. 10 gear ratio?

 

[Chipstien]

BFG 315's are 599 rev\mile. Is this not a valid selection?

 

[brickerd]

Had mine reset a couple weeks ago and they claimed that they entered 601 without a problem, although I didn't see them do it in person.



As far as if it's correct or not, it seems like it is by watching the mile-markers, etc. but I haven't checked it with GPS yet. The dealer did claim that they checked it against another car. As far as costs, they did it for free.



As an interesting side note, it seems that when the revs-per-mile are changed it relies on the ABS computer. What I mean is this: I had to have my front left U-Joint replaced and when they fixed it they broke the ABS sensor and had to order one; this was the same time that they entered 601 into the computer. I drove it for 3 days without ABS and the speedo was still off ~10%, as it was before the change. After they replaced the ABS sensor and it was working again the speedo was correct (or as correct as it is today). It's like it just used a default setting or something.

 

[David Muench]

Originally posted by Tejasdge

When I had mine re-calibrated by the dealer, they said that 636 revs per mile, if I recall correctly, was the closest they could get to 601. I'm now off by 5% verified by mileposts and GPS. While my warranty will last 5% longer I would rather have it correct. Seems like the ABS isn't happy with the difference, and wants to lock up instead of modulating the brakes when you really stomp the whoa pedal. Is my dealer full of it or is that as far as you can recalibrate with the 4. 10 gear ratio?

I think there used to be a limit in the computer, because a few months ago when people were trying the lowest it would accept was 636. Now all of the sudden it works. My guess is they upgraded the scan tool software to allow a lower number.



601 is the right number for a BFG 315/70-R17 AT/KO, according to BFG.

 

[Tejasdge]

I'm working on my repair and TSB list and will bring this up with them when I have all my work done. Man I hate going to the dealer. :{