Helps - revs per mile
07-09-2009, 04:59 PM
#1
6th Gear Member
Thread Starter
Join Date: Nov 2007
Location: Montaner
Posts: 6,193
Helps - revs per mile
I just got some 295/45/R18 tires on the car and I'm not sure what to set for revs per mile in the tuner.
Nitto's site for the NT05 says 730 revs per mile.
Discounttiredirecto's calculator says 708 revs per mile.
The spreadsheet I have for calculating this says 708 revs per mile.
Is it 708 then? And should I take this figure and subtract 3% to get a more correct figure since the manufacturers rate this without a load on the tire?
Nitto's site for the NT05 says 730 revs per mile.
Discounttiredirecto's calculator says 708 revs per mile.
The spreadsheet I have for calculating this says 708 revs per mile.
Is it 708 then? And should I take this figure and subtract 3% to get a more correct figure since the manufacturers rate this without a load on the tire?
07-09-2009, 05:24 PM
#3
3rd Gear Member
Join Date: Feb 2008
Location: Anchorage, AK
Posts: 987
I just got some 295/45/R18 tires on the car and I'm not sure what to set for revs per mile in the tuner.
Nitto's site for the NT05 says 730 revs per mile.
Discounttiredirecto's calculator says 708 revs per mile.
The spreadsheet I have for calculating this says 708 revs per mile.
Is it 708 then? And should I take this figure and subtract 3% to get a more correct figure since the manufacturers rate this without a load on the tire?
Nitto's site for the NT05 says 730 revs per mile.
Discounttiredirecto's calculator says 708 revs per mile.
The spreadsheet I have for calculating this says 708 revs per mile.
Is it 708 then? And should I take this figure and subtract 3% to get a more correct figure since the manufacturers rate this without a load on the tire?
The problem with using straight math, is that tires are not built to the exact size they are marked, there are acceptable variances in manufacturing.
Last edited by AK_Kayaker; 07-09-2009 at 05:33 PM.
07-09-2009, 06:18 PM
#5
6th Gear Member
Although you have multiple #'s, the tuner (at least my XCAL2) let's you set it to the nearest 10's of RPM. I suggest you use a GPS to get your true speed and pick the value that gets you closest. I used the manufacturer's RPM's for my tires and I was still 2 MPH low on the speedometer at 60 MPH true speed.
07-09-2009, 08:47 PM
#8
2nd Gear Member
Join Date: Nov 2008
Location: Va
Posts: 171
Use the manufacturer's number. I had the same problem with my tires. Tire Rack had one number and the manufacturer listed another. Turns out BFGoodrich was right.
If you're really confused, then try and call the manufacturer. You might also get an idea from other tires that are the same size. Rev per mile isn't the same for all tires, even in the same size, but it should be close for most.
To make matters worse the speedometer can sometimes be a bit off from the factory. My ECU reads a few mph higher than my speedometer at highway cruising speeds according to my Aeroforce Gauge.
If you're really confused, then try and call the manufacturer. You might also get an idea from other tires that are the same size. Rev per mile isn't the same for all tires, even in the same size, but it should be close for most.
To make matters worse the speedometer can sometimes be a bit off from the factory. My ECU reads a few mph higher than my speedometer at highway cruising speeds according to my Aeroforce Gauge.
Last edited by mustangtestuser; 07-09-2009 at 08:51 PM.
