Speedo correction for larger tires?
When is it necessary to get a speedo correction for larger tires? I went from a 265/75 to a 285/75 both 16 inch. Would the height even change?
Forum Discussion
Many people have mentioned calibrating the speedometer, but I prefer to calibrate the odometer.
I have never driven a rig where the speedo and odometer match, some are off by 2-3 mph. My DD VW is off by 2-3 mph at 70 but the odo is dead accurate.
For calculating mileage, maintenance, and true odometer readings I suggest calibrating the odometer over a 100-200 mile stretch and learning the small speedo error.
My sig truck is calibrated within 0.3%, and reads about 1mph fast at 70. It's more accurate IMHO, and keeps the wife from speeding and I just set it based on the speedo and I'm not going as fast.
Many manufacturers post rev/mile data, this is far more accurate to start with than tire math.
If you are getting a 1/2" of squat your tires are overloaded or under inflated.
I will see a small change empty to loaded, but never even 1%.
I have never driven a rig where the speedo and odometer match, some are off by 2-3 mph. My DD VW is off by 2-3 mph at 70 but the odo is dead accurate.
For calculating mileage, maintenance, and true odometer readings I suggest calibrating the odometer over a 100-200 mile stretch and learning the small speedo error.
My sig truck is calibrated within 0.3%, and reads about 1mph fast at 70. It's more accurate IMHO, and keeps the wife from speeding and I just set it based on the speedo and I'm not going as fast.
Many manufacturers post rev/mile data, this is far more accurate to start with than tire math.
wintersun wrote:
Check your speed with a GPS or smartphone with GPS and see how accurate your speedometer/odometer are with the stock tires. I did not realize it but with a camper load the actual speed was 2 MPH less than indicated thanks to the tires squatting and not being as tall. Only takes a 1/2" of squat to affect the speedometer accuracy by 4%.
If you are getting a 1/2" of squat your tires are overloaded or under inflated.
I will see a small change empty to loaded, but never even 1%.
