TireSpecLab helps drivers in the United States answer the questions that come up before they buy tires or wheels: will this size fit, how much taller is it, what happens to my speedometer, and how do two tires really compare on paper.
What you will find here
- Calculators for tire sizes and wheel offset, each with its formula and its limits shown on the page.
- Size and fitment guides that work through real size changes with the numbers.
- Load and speed rating explainers based on the official rating tables.
- Tire comparisons built on manufacturer specifications and credited published tests.
What we do not do
We do not run our own braking, noise or treadwear tests, and we never write as if we had. When a guide mentions a test result, it names and links the organization that ran the test. Calculated figures are nominal values from the size code; real tires vary by brand and model, so we always point you to the manufacturer’s specification sheet for the final check.
How our content is researched, written and corrected is described in our editorial policy.