I dont think the speedo is maybe 2mph off.......should I have it recalibrated ??

 

I have a 2nd gen...but I went up to 285s, and my speedo is actually more accurate now, then with the 265s! go figure

 

I never did mine, just be aware of it when in a speed trap area. I figure that I just rack up that many fewer miles on the odometer...... Also, it is off more than you think, probably about 5 mph when doing 70.

 

when my 295's were new, it was off 5mph at 70

 

I would, had mine done for the 315s and then for the 285s. I like the OD and trip to be correct. Not sure if it really affects any shift points, but just feel better knowing that the computer is seeing the right speed/rpms. Just my .02.

 

I have GPS'd my 33-12.5-17 ProComps and they are Exact to what the speedo says! Onlt thing that I can think of is that the Speed Gauge was off from the factory!! These are roughly the exact same size as 285's!! Just GPS the truck with teh new tires and see what it says! JB

 

yeah, I gps'ed it with 295 nittos and it was 4-5 mph off. They were a 33in tire. Took the tires back and swapped out for 285's , so it shouldent be much off. Was thinking more along the line of shift points, but our trannys are crazy and have their own minds anyway

 

My shift points changed when I had it recalibrated for 285's.

 

for better or worse ??

 

X2, speedo is bang on with the GPS 305/65-17 (33x12.5-17) PROCOMP X-AT's,...when I had the 285 BFG AT's I was 2% over...

 

Why not have it accurate?


Remember guys, it's not a set value difference. It's a percentage. If you're 5% off at 30mph that's only 1.5mph, but at 70mph, it's 3.5mph.

 

The shift points are higher, so it depends on what I'm doing at the time. TC lock is now at 52 instead of 49. It really didn't changed things much, but it seems like the computer now compensates for a little planned power loss with letting the motor get a hair further up in the power band.

 

... up to you isn't it?

Me? I had the dealer do redo it when I had it in for a recall, I like things to be accurate.

 

Anyone know how much it costs to have the dealer re-calibrate your speedo if you take it in? I've tested mine by driving next to 3 different vehicles at 65-80 MPH and I was spot on but I'd like my odometer/trip to read right...

Thanks for the input!