Am I putting more or less miles on with larger tires?

[ajjaaron]

For all of us that have increased our tire size are we putting more or less miles on our 4Runners? I understand that if you use this link http://www.csgnetwork.com/tireinfo4calc.html you can calculate the difference in tire size from stock size. In my case 3.41% difference. Correct me if I am wrong but that means that I am actually going 3.41% slower than my speedo says. So would that also mean that I am putting 3.41% less miles on as well?

 

[qballjr13]

I think that is right. The bigger the diameter, the slower the rotation. So it would make sense that they are traveling 3% slower than the stock diameter wheels and tires. Use this calculator it really is great!

http://www.1010tires.com/TireSizeCalculator.asp

 

[ProMed]

In my case 3.41% difference. Correct me if I am wrong but that means that I am actually going 3.41% slower than my speedo says. So would that also mean that I am putting 3.41% less miles on as well?

I think you may have the speed backwards. If your speedo says 60mph then you are actually going ~62.1mph. However all factory speedometers read a little high so you may be close to perfect. You are correct that you are putting 3.4% less miles on the odometer. There should be no factory odometer error since I believe that is regulated by law.

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

 

[ajjaaron]

According to this link http://www.1010tires.com/TireSizeCalculator.asp it states that the Speedometer Difference: 3.403% too slow.

 

[ProMed]

According to this link http://www.1010tires.com/TireSizeCalculator.asp it states that the Speedometer Difference: 3.403% too slow.

Correct the speedometer is reading 3.4% too slow. That means your actual speed is 3.4% faster than what the speedo is reading.

 

[ajjaaron]

Re: Re: Am I putting more or less miles on with larger tires?

I think you may have the speed backwards. If your speedo says 60mph then you are actually going ~62.1mph. However all factory speedometers read a little high so you may be close to perfect. You are correct that you are putting 3.4% less miles on the odometer. There should be no factory odometer error since I believe that is regulated by law.

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

So back to another statement about putting less miles on the 4runner is not correct because it is regulated by law. Could you explain to me how that system works.

 

[ProMed]

Re: Re: Re: Am I putting more or less miles on with larger tires?

So back to another statement about putting less miles on the 4runner is not correct because it is regulated by law. Could you explain to me how that system works.

No you were correct on the odometer being slow. The odo will show 3.4% less miles with the larger tires.

Bone stock most cars/trucks are actually actually going a few to several mph less than indicated on the speedometer. You will see in several of the major mags they will test the speedometer and show the indicated vs. actual speed. Since you have larger tires that slow the speedometer down 3.4% it should be closer to your actual speed. I have not read on here what the factory speedo error is on the T4R. My last Honda streetbike was around 5% and my Tundra was around 2-3% if I remember correctly.

The odometer on the other hand must be accurate since this is supposedly regulated. So your 3.4% difference will transfer directly to the odometer which will now read 3.4% slow.

Both your speedometer and odometer will read 3.4% too slow with the larger tires. So you will actually be driving 3.4% faster/farther than those gauges would normally read with the stock tires.

Hope that makes sense!

 

[rolla_dink]

pure and simple, yes you are putting less miles on your truck with larger tires then you had before.

your speed that you read on your speedometer is actually reading from the transmission which is preset to a certain sized tire.

also as stated above the old 60mph you think you are travelling is indeed faster if you were being clocked by a radar or by ground speed.

 

[wolfgang]

I've not heard anyone mention having the dealer adjust the computer to compensate for the larger tires. Since all is now computer controlled isn't this a simple software controlled change? In old days of cable driven speedometers it mean changing the speedo drive gears at the transmission or adding an adjustment box - but don't computers now simplify the adjustment?

 

[RonMAIDEN]

I have about 1" taller tires and my speedo reads two mph faster.

 

[DaBoostCreep]

I have about 1" taller tires and my speedo reads two mph faster.

I dont see how thats possible. The VSS is installed in the transmission, and the RPM of the VSS is dependent upon the tire size.

You realize that:
Output shaft RPM is relative to driveshaft RPM, which is relative to differential RPM, which is relative to axle RPM, which is relative to tire RPM.

Its as simple as this. A larger tire means the rotating assembly from the output shaft back, and actually the engine for that matter are spinning less RPM to achieve a desired MPH. Its impossible to have a speedometer read faster when taller tires are installed unless your VSS is malfunctioning.

 

[RonMAIDEN]

Oooops,I actually meant slower as read by the roadside radars. Under 50mph it's still pretty much dead on but at 60mph+ it reads two mph slower.