well yes if you lower the psi down your footpring gets larger but your height gets a touch less as well.Greybrick wrote:I've read the same info; that the US built PF OR's with 265/75R16 size are about 31.5" diameter and that all of the other PF model odometers are set for that size, not sure if thats true though as I've never had these 245/75R16's checked in relation to odometer accuracy.
As an aside question do any know if tire diameters vary depending on the amount of air pressure in them.
PSI no, MPG yes. The optimal choice is to travel over a measured mile (if you can find one) that your local gub-ment utilizes to verify speedo's, or hit up one of the AAA events that do the same. Once you have that true MPH value you can extrapolate any other number you want from your display MPH/MPG.Captain caveman wrote:I want to know with this mess up the dash computer as far as mpg read out and psi?
I'm pretty much settled on the belief that all the computers are set to the SE-Offroad's 31.5" wheel size. My stock tires made the speedo disagree with my GPS for a 3+mph @60. Once I went to the 31.6" the two are just about equal.Captain caveman wrote:I compared speedos with two other cars tonight and I found that my PF is off. At true 40mph my PF showed 37-38mph and at true the PF showed 62-63.
I check this with the tire size of my PF 265/65r17 and the Offroad 265/75r16 and my calculations are correct. my Se has the speedo calculations of the Offroad SE Pathfinder.
So this will show that my dash computer is off for MPG and Trip calculator.
This all still falls in the +/-5 or 6 percent fug factor from Nissan.
I would really get it checked. I still can't believe the MPG numbers that you've mentioned, and really think the tires are coming into play with everything.Greybrick wrote:I've read the same info; that the US built PF OR's with 265/75R16 size are about 31.5" diameter and that all of the other PF model odometers are set for that size, not sure if thats true though as I've never had these 245/75R16's checked in relation to odometer accuracy.
I think this is because you have a 31" tire not like me that has a 30.6".NVSteve wrote:I kept an eye on the speedo and my portable GPS for about 1600 miles worth of driving the last week. I'd have to say they both reflect the same numbers. The GPS is just too accurate, which meant that I had to really position the speedo needle dead center of any of the tick marks in order to do a comparison. That's with 265/75/16s.