GARAGE CALCS FOR THE HOME BUILDER

Plus-size tire calculator

Moving to bigger wheels? This lists the tire sizes that keep your overall diameter close to the original, so your speedometer and gearing stay right.

Free, no sign-upUpdated September 2026
Your numbers
Original tire
New wheel

Original diameter

Tire sizeDiameterDifference

How plus-sizing works

A bigger wheel needs a shorter sidewall to keep the same overall diameter. The calculator tries every common width and aspect ratio on your new wheel size and keeps the ones within your allowed difference, closest first.

Not every size listed is actually made, and widths need to suit the wheel's width. Confirm availability with a tire retailer, and use the wheel offset & backspacing calculator to check the new wheel's fitment.