Tire Size Calculator

I have 225/50 VR16 tires on my car right now:
I want to see how much difference there would be if I installed a
different size, Example:  245/45 ZR17.

My data inputs would look like this:

Tire Width
Aspect Ratio
Wheel Diameter
Original Tires 265 MM 65 Percent 17 Inches
New Tires 245 MM 45 Percent 17 Inches

Input Your Data In the "AnyCalculator" Tire Size Calculator Below. (Estimate Of Actual Speed ONLY!)

Please Select The First Six Values Then Click the "Calculate" Button
Tire Width
Aspect Ratio
Wheel Diameter
Original Tires
New Tires

These Values Will be Calculated:
Original Tires Diameter (mm) Diameter (in)
New Tires Diameter (mm) Diameter (in)
Difference Diameter (mm) Diameter (in)
This Change Represents: %
Speedometer Error:
At 30 mph Indicated Actual Speed is: mph
At 60 mph Indicated Actual Speed is: mph
At 90 mph Indicated Actual Speed is: mph


This calculator is designed for information related to tire size changes and the impact they have on the calibration and accuracy of a speedometer. It determines speedometer error at different speeds using tire size information based on published tire dimensions as given by the standard US tire system (i.e. 205/45-ZR16). All calculations are based on the assumption of a new tire (as opposed to a used tire) where the numbers on the tire accurately represent the dimensions.

Tire width - Also called the tread width, this is the width of your tire's treaded area, measured in millimeters. Typically, this will be a high number that is displayed first on a tire.

Aspect ratio - Also called the profile, this number is a percentage. Usually the second number displayed on a tire, this is the sidewall height divided by the section width.

Wheel diameter - This number refers to the rim size of your vehicle's wheel. It's usually measured in inches. 

When purchasing new tires for your car or truck, it's always a good idea to stay within the limits set by your vehicle's manufacturer. Different tire sizes can affect many of the systems in your vehicle.

The answers to your calculations are only an estimate and should be verified by traffic accident experts if you were in an accident. The estimate by accident experts will be different and more accurate that any online calculator. Do not rely on this online calculation only, it is just an estimate example.



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