Speedometer Re-Calibration Complete.

[67guzzler]

Put on the LT315/70R17D Cooper Discoverer ATR's last week.



#ad




Went to the dealer this AM to set my revolutions per mile. The service manager hooked me up with the 1 service advisor that was really good with the scan tools.



The first scan tool had a bad cable and would constantly disconnect and reconnect. Pitched that and then came out with the super modern StarScan tool. But it didn't have the proper body style so it couldn't configure properly. Back to the old style tool. They only had one left and it was actually being used to diagnose a problem on another person's truck.



Finally got ahold of the 1 and only working unit for my truck he went into the ABS section and then he changed the revolutions per mile from 657 (standard factory for the LT265/70R17E tires) to 601. He went for a test drive with me and I was 20 mph way over. I asked him if he messed with the axle and he said that it asked him what it was and he set it to unknown. On the road we pulled over and he set it the axle back to 11. 50 and all is well.



I'm right at 2000 rpm at 70 mph which is about right for the 315 size, G56 (. 79 OD) and the 3. 73 rear. It might be reading a hair fast (maybe should have been around 605) but I'm fine with that.



I guess it goes to show you that nobody and no situation is perfect but if people want to go the extra mile you can get things done. Spotted the service advisor $20 for his trouble, made a friend and all is well with the world.....

 

[67guzzler]

601 Revs Per Mile --

601 was the magic number for the LT315/70R17D Cooper Discoverer ATR's. Their website reported the tire height at 34. 85" but it did not publish the revolutions per mile so I had to guess.



This morning I got the OLD Garmin GPS 45 fired up and at an indicated 70 mph on the speedo the GPS is returning 69. 6 mph.

 

[LightmanE300]

I'm not sure what to make of mine. I had it reset to 593 revs per mile as according to Toyo's website for the 35/12. 50 R18 tires. My garmin etrex gps says that it is spot on, as do the police things they have by the road that display your speed to discourage speeders. My other gps unit shows me going 2 mph slower than the speedo registers. I know I'm pretty close, but I don't want to be going any slower than the speedo registers, putting more miles than I actually drive on the truck... Ack, have any of you tried with multiple gps' , I am having trouble as to which one to believe!! :-laf