How much is the speedometer off?
 

Now that I have my speedometer working I am curious to know how much the MPH is off with 35s and 4.88 gears? I have not seen a radar sign locally to drive through it to see what I am truly running.

Thanks

Mine is dead on with ~35's and 4.88's...use the mile posts on the side on the interstate to help gauge it....so to speak...:D

Good tp hear. I am changing the front main seal now so once i can elminate the massive oil leak i cna take it and get it on the road more than a few tests.

depending on your actual tire diameter, you should be within 100 rpms of 4.10's and 225/75/15's, at 65mph speeds. I would say dead on up to maybe 1 or 2 miles per hour on the freeway. Close enough to not worry about it.

http://www.grimmjeeper.com/gears.html

Thanks guys. Cant wait to go for a long ride.

Jason, that site is freakin nice! :great:

I'm off about 1 mile in 10 with the 4.56's and 31inch Treadwrights (20mph on the speedo is 18mph, 50mph on the speedo is 45mph etc). At 110 on the speedo I'm running 99. Don't even ask me what it is when the speedo is pegged......

I think the actual tire size (rotations) on the ground is the needed information. Most manufacturers label a tire as a "35" but it may be smaller/larger in fact. Of course as a tire wears it changes.

Yeah ricky. My tire is a (30.9) and its got me 1 or 2 off on the freeway. Most "31's" are about 30.6. regular size 32's (which are about 31.7) will get you right where you need to be. I ordered my tires before I started messing closer with that gear calculator.

Mine are 34.9". Is that close enough to 35"? I'm just curious...you know...:D

Sure. Then I can call mine 31's. :D

find someone with a GPS that you can borrow if you want to know for sure. The GPS will tell you how fast you going. :)

My TR's are 30.7inches although advertised as 31's. I didn't think about it much until I went through one of those areas that had a "speed sensor" with a huge display of your speed. The thing read 46mph and my speedo read 51. I must have gone past that thing three or four times at different speeds to see what I was actually doing. And here I thought with the speedo needle pointed at the odometer dials I was hauling buns.....

I got one on my phone. Got an app for that. hehehe

Gonna go for some 265/75/16's next time....

its gonna change more at higher speeds. say your gearing and tires puts your speedo off by 10% your only gonna show 1 mph off at ten 2 at 20 3 at 30...10 a 100. you just need to find what percentage you are off by which can be done many ways. if you dont wanna factor in weight and diameter and what not on paper have a buddy drive beside you and have him go exactly 20 or 60 mph or something like that and see what your speedo says at that speed. then just figure out what percentage your off by. if that makes sense?

Yep, makes sense. helps to do your homework before you spend 800 bucks on tires and have someone follow you though. Thats what we are getting at. :great:


I did the gps in the car though. Wait, what if your buddies rig is off, too? :D

ya i did mine for my swampers on paper before i bought them but the way i understood it he already had them. and good call i just assumed my gfs car was close enough. i do agree with gps cant argue with that. i was just trying to make a point that it may be irrelevant at 10 mph only being 2 miles per hour off but when your at 50 and now your actually going 60 but you think your only going 52 it can be an issue.

Very true. I kind of like where I am at. If I just run the "5 over" on the freeway, its really like 3 over, and that usually has others getting pulled over instead of me. :D

Got to thinking about this thread and realized that none of us (4banger or 6shot) were ever concerned about going too fast.... *laugh* It is what it is and these little rigs are NOT fast enough to break any land speed records. Good idea to know how fast you are going but it really doesn't matter when you're getting passed left and right on the highway.

Indeed. I had a crotch rocket bout 5 years back, got it up to 140 with one more gear to go. I decided against that last gear. Drove it home and put it up for sale. No point in being stupid. Now I don't even have the option of going fast. It IS pretty funny.