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w6bauer
04-23-2009, 05:21
Does anyone know the conversions for speed and odometer compensations when tire size is changed? My rig came with 245/75R16s, went to a 265/75, now I am running a 285/75. Would be helpful for keeping track of actual miles on rig, speed, and fuel economy. Appreciate it.

Will
DennisG01
04-23-2009, 11:43
I had only ever measured at 70mph. At that speed, your odometer will measure 3% slower than actual speed. I verified this with a GPS; before and after. I then bought the Feature Articles book (either '99 or '00) - it has the info on adjusting your VSSB. I think this is still available in the Member's Area.
w6bauer
04-24-2009, 04:33
im guessing that 3% was on the 265s? would it be correct to say 6% for a 285? I am about to take a 7 hour trip to indianapolis with my sister in trail in her mazda so i guess i can use her odometer before and after reading and compare that to mine.


Will
DennisG01
04-24-2009, 05:31
Oops, sorry - I misread your post. Yes, based on my basic calculations, should be about 6% at 70MPH. The faster you go, the more it's off.

On edit: I plugged in "mileage calculator tire" to google and found this: http://www.performanceprobe.com/index2.php?redirect=http://www.performanceprobe.com/misc/index.php?do=calc&page=tire