How it works

TireFlows

Get diameter, speedometer impact, and alternate sizes — free, no signup.

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.1%

Safety Rating

Safe

Within the recommended 3% safety margin.

The 3% rule is a common reference — not vehicle-specific advice. How it works

Speedometer Error

-1.1%

Absolute Difference

-0.36"

Speedometer

Assumes Tire 1 is what the speedometer is calibrated for. Shows approximate actual speed if you switch to Tire 2.

Reading (mph)Actual (mph)Difference
2019.8-0.2
3029.7-0.3
4039.6-0.4
5049.5-0.5
6059.3-0.7
7069.2-0.8
8079.1-0.9
Tire 1Dia. 32.81 ″Rim 22 ″5.40 ″Width 12.01 ″Revs/Mile 614.7Circum. 103.1″Tire 2Dia. 32.45 ″Rim 22 ″5.23 ″Width 11.61 ″Revs/Mile 621.5Circum. 102.0″
Tire 1
Specification
Tire 2
32.81"
Diameter
32.45"
12.01"
Width
11.61"
5.4"
Sidewall
5.23"
103.067"
Circum.
101.953"
614.7
Revs/Mile
621.5

How results are calculated

Tire dimensions are calculated from the metric size format (width / aspect ratio / rim diameter). Diameter, circumference, and revolutions per mile are derived mathematically — no fitment or vehicle data is used.

The 3% rule is a general reference for acceptable diameter difference, not a guarantee. Always check your vehicle manual or consult a tire professional.

How it works