Find Out How Much Your Speedo Is Off

[82chevy350]

http://www.discounttire.com/dtcs/infoTireMath.dos

 

[Jaymez]

The tire size calculator at Miata.net is another great resource.

http://www.miata.net/garage/tirecalc.html

 

[jake wells]

Good find jaymez and 82chevy 350

 

[Mr Clickerson]

GPS or chase car. :3

You can find out exactly how far off your speedo is at any speed by simply getting one comparison. So, since neither of those "calculators" take gearing into account, they're not very accurate, unless you have stock gearing and stock speedo gear, which is something many of us don't have.

 

[crazy4offroad]

Here is a really good gear calc.
http://www.grimmjeeper.com/gears.html
A little complicated but anything worth it's salt is. Once all the numbers are punched in you can find out what speed to expect at what rpm.

 

[Mr Clickerson]

Here is a really good gear calc.
http://www.grimmjeeper.com/gears.html
A little complicated but anything worth it's salt is. Once all the numbers are punched in you can find out what speed to expect at what rpm.

Just looking at that thing gave me a headache.

 

[DesertBob]

I just used my GPS to calcuate my percentage difference. Is there a place to get new speedo gears to bring it back into sync? If so, is there a chart for picking the right gear? I have a SM465 trans, NP208 Transfer Case and am running 3.42 gears in a 14bolt/10bolt axle combo. Tires are 285/16.

 

[89Suburban]

 

[Mike D]

Another way to determine speedo error is to drive on the Interstate highway. Bring a friend with a watch with a second hand. If you concentrate on driving 60 mph according to the speedo, have your friend time in seconds the time it takes you to pass each mile markers on the Interstate. If you are truely doing 60 mph you will pass a mile marker every 60 seconds. Adjust your speed (faster or slower ) so that you pass every mile marker in exactly 60 seconds. The difference of 60 minus your speedo is the error.

 

[Illuminati]

I wish there was a conversion that could be done just to compensate the speedo and be done with it....my speedo is 10mph off from the tires and just watch that and the GPS. it is a pain in the ass tho