I'm assuming yes. By the same percentage as the tire size increase. Or is it run by the transmission? And not related to the tire size? I have a hard time thinking that since the tires jacked up my speedo

Absolutely, the odometer is geared off of the speedo itself. The speedo gets it's input from the Transfer case so any changes after that point of the drivetrain(like larger tires) affects both the speedo and odo as they are mechanically linked.

That's what I thought. Thank you, so my new tires are 14 percent larger. So I'll just add that to my trip Odo meter to get my mpg. You guys are always so helpful!

Did you regear anything?  Axles or t-case?  If so, you will need to factor that in too.

I went from the stock Samurai tire height of 26.3" tall (205/70/15) to 31.8" tall tire (32x11.5x15).  It changed about 21%  So, if I changed nothing else on my Samurai my Spedo/odometer would be off by roughly 21%.  At 50mph on the spedo I woud actually be traveling just a hair over 60mph.

Now, I changed my t-case gears to compensate for this.  I chose the 6.5:1 gears that reduce the hi-range and low range both.  My hi-range was reduced 20% as posted on Lowrangeoffroad.com.  In theory, I should almost break even on my upgrade of larger tires.  What I have found is that I'm still off by a good margin and I'm trying to nail down exctally what that margin is.  I've used a couple of different GPS units and my phone and I'm getting inconsistent numbers.  For some reason I still think at an indicated 50 mph I'm traveling about 55mph.  I'm trying to get it narrowed down so I can make the mental calculations on the fly.

Rob

Nope haven't re geared. A 4.2  t case gear is in the works but that won't affect my high range

What t-case are you going to run?  If it's a Samurai t-case with different gears, I'm about 90% sure your hi-range will be affected.

Here is a link to Lowrangeoffroad.com website for reference:

http://www.lowrangeoffroad.com/index.php/suzuki/samurai/transfer-case.html

Everyone of the t-case gear sets changes both the hi and low range gear ratios.  Can you check your gear set and get back to us?

Rob

Its a sidekick so the gears will not change the high range. Sadly. But yes if it was a Sammy the gears would reduce high and low

Yep, that would have been important information to have up front.


Rob

i have 31's on my sidekick, and had gotten used to interpreting the speedometer.
i put a later model transfer case in it, and was surprised to find the speedo is now pretty accurate.
mabe this is special case(i have 5.62 diffs), but there must be a few differently geared speedo drives.

i have 31's on my sidekick, and had gotten used to interpreting the speedometer.
i put a later model transfer case in it, and was surprised to find the speedo is now pretty accurate.
mabe this is special case(i have 5.62 diffs), but there must be a few differently geared speedo drives.

Yes, there are several different speedo gear configurations, depending on the axle ratio.....4.30, 4.62, 5.12, 5.38, 5.62.

I changed speedo drive gears when I rebuilt mine ( tcase) . I used a different set of speedo gears once I had the case apart, I believe they were from a case that mated to a auto trans with the 4.3 axle ratio. Once I had it back together I found my speedo was much closer to being accurate with 32" tires. Go figure.