Checking my speedometer

Question

I think my speedometer is off. I have an 89 Supra and when i ride in other cars and trucks it feels like were going faster than i would be in my own car...

Answer 1

Have a friend ride next to you in their car and pick a speed and see if it matches.

Answer 2

Check your vehicle's tire size. If the tire size is different from the manufacturer's recommendation, your speedometer may be reading too fast or too slow.



Find a road where the speed limit is at least 60 mph. Most of the time this will be on a freeway or interstate highway. You will need to find a time of day or night when the traffic load of the road is the least congested.

Get on the road at the selected time and ensure that you can maintain a speed of 60 mph. Once you have reached 60 mph, watch for a mile marker. On most interstate highways, there are markers every mile. As you pass one of the markers. note the mile number and start your stopwatch. Continue driving steadily at 60 mph until you reach the next mile marker and stop the stopwatch.

Note the number of minutes and seconds that it required you to drive 1 mile. If it took you less than 1 minute to travel this distance then your speedometer is reading a speed less than what you are actually traveling at. If the time it required you to drive the 1 mile is more than 1 minute, then the speedometer is registering a speed higher than the speed you are actually driving at. To double-check this test, repeat the test but instead of 1 mile, measure the time to drive 10 miles. This will give you an average of ten 1-mile increments.

Or hook up a computer scanner to the vehicle and drive down the road, the scanner will show the true mph and you can compare that to your speedometer.

Or borrow a friends GPS and use that the same way that you would used the scanner, GPS will also show the true reading.....

Answer 3

Speed perception varies depending on the car. I had a 2001 Camaro and a 2001 S-10, and the Camaro felt a lot faster. If you want to verify your speed, try finding one of those things the police put up that show how fast you're going (they usually put them in areas where speeding is a problem). Another option is to use a pace car. Have a friend drive next to you at a predetermined speed and compare them.

Answer 4

go to an interstate with mile markers. drive on cruise control at exactly 60 mph. when you pass a marker , set timer, it should be 1 minuite when you get to the next mile marker<