How do you figure out how much your speedo is off with larger tires.
 

I have a 95 4Runner that I have put 32x11.5 tires on and im wondering how much it throws off your speedometer. It originally had 31x10.5 tires so it cant be off much but i still want to know so I dont get a ticket.

try the search button first, speedo calibration or similar should get you pretty close to what you are looking for. failing that, www.4crawler.com , look in the index or better yet, start reading at the first page. there is plenty of information relevant to the toyota trucks that will set you on the right path.

lee

its probably closer to accurate now than it was befroe

Or . . . get yourself a GPS unit! :D

Google search TIRE CALCULATOR. You should find one that will let you do a comparison of tire sizes and also determine the speed differences.

You could have somebody in a stock vehicle drive next to you on the highway and have them holler at you when they reach 55 (or whatever). Take notice of your speed and remember it. You can do this in intervals of 10mph if you want.

Kinda the redneck way, but oh well. :hillbill:

Ask the cop when he pulls you over...

Here is the on-line tire size/gearing/speedo calculator on my web page:
http://www.4crawler.com/4x4/4LoCalc.shtml

Or the quick and dirty way is to just take the ratio of the tire diameters, 32/31 = about a 3% error, i.e. you'll be going 3% faster than the speedo indicates, assuming is was correct before.

Get on the road w/ a buddy and a couple cell phones and just see. Mine is about 5 mph off, i.e. my speedo reads 65 and I'm doing 70, w/ 37 MT/Rs and 4.88 gears on a 5 speed 4 banger 85.

:guitar:

Time some mile markers - 60 mph = 60 seconds per mile.

convert angular velocity into linear velocity!!

GPS, as mentioned earlier, or find a radar trap. Stop and explain what you want, and why. Take a long run at him with your cruise control set at a fixed speed, on a level road, and then flash your headlights at him when you're a quarter-mile away. He'll give you an accurate reading.