Plus Sizing Your Tires
Go up a rim size without throwing off your speedometer.
Plus sizing means fitting a larger-diameter wheel with a shorter-sidewall (lower-profile) tire, while keeping the overall tire diameter close to the original so the car still drives correctly.
Why plus size?
A bigger wheel with a lower-profile tire improves cornering response and gives a more aggressive look, because the shorter sidewall flexes less in turns. The key is diameter: keep the new tire within about 1-3% of the stock overall diameter.
The Plus-0 / Plus-1 / Plus-2 ladder
- Plus-0 — wider tire on the same rim, same aspect drop (~5 points) to hold diameter.
- Plus-1 — rim one inch larger, tire ~10 mm wider and ~5-10 points lower aspect.
- Plus-2 — rim two inches larger, tire ~20 mm wider and ~10-20 points lower aspect.
How to keep diameter
Overall diameter = rim x 25.4 + 2 x (width x aspect / 100) mm. To hold diameter as the rim grows, the sidewall must shrink; each inch of rim needs roughly a 5-10 point drop in aspect ratio for a typical width. Use the tire calculator to compare any candidate against your stock size and check the percentage.
Watch the trade-offs
A shorter sidewall rides firmer and is easier to curb-damage. Make sure the new wheel clears the brakes and fenders, and stay within the load index your vehicle requires.
Frequently Asked Questions
What is plus sizing?
Plus sizing fits a larger wheel with a lower-profile tire while keeping the total diameter near stock, so speedometer and gearing stay accurate.
How much can diameter change?
Most shops keep the new diameter within 1-3% of the original. Beyond that, speedometer error, fender rub, and gearing changes become noticeable.
Is plus sizing safe?
Yes when done within diameter and load-index limits and with correct fitment. Confirm brake and fender clearance before buying.