GarageCalc

GarageCalc is a free collection of automotive calculators and practical reference pages. It is a personal project from Lithuania for an international audience. The tools are available in a web browser without creating an account or installing an application. They help vehicle owners work through measurements and calculations, while showing the assumptions that affect the result.

The tire comparison tool takes two metric tire sizes and compares nominal overall diameter, sidewall height and circumference. It also estimates the relative speedometer change if calibration remains unchanged. These calculations describe size-code geometry. They do not establish the actual rolling circumference of every tire carrying that size marking. For an exact tire model with published data, optional manufacturer revolutions-per-mile inputs let the reader distinguish rolling information from a geometric estimate.

Other wheel and tire tools address related questions, such as understanding wheel offset or reading a tire date marking. The date-code reference interprets the final four digits of a DOT date code as the manufacturing week and year. A manufacturing date is different from the date a tire entered service, and age alone cannot establish condition. Readers still need the tire and vehicle manufacturers' guidance and an appropriate inspection.

GarageCalc also provides fuel-related calculators and car maintenance guides. These are intended to make a calculation or a practical explanation easier to follow. A useful workflow is to collect the actual vehicle or tire specifications first, enter the measurements in the relevant tool, then read the formulas and limitations alongside the answer. Estimates depend on the inputs and should be checked against the original specifications.

The site is an informational reference rather than a workshop, a parts retailer or a vehicle-specific fitment certification service. A small nominal diameter difference does not prove that a wheel and tire combination is suitable. Approved sizes, load ratings, wheel dimensions and physical clearance still matter. Maintenance guidance does not diagnose an individual vehicle remotely. GarageCalc is useful for comparing measurements and understanding the arithmetic before discussing a choice with a qualified professional.