How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.66%

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

1.66%

Absolute Difference

0.53"

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
2020.3+0.3
3030.5+0.5
4040.7+0.7
5050.8+0.8
6061+1
7071.2+1.2
8081.3+1.3
Tire 1Dia. 31.92 ″Rim 22 ″4.96 ″Width 12.40 ″Revs/Mile 631.8Circum. 100.3″Tire 2Dia. 32.45 ″Rim 22 ″5.23 ″Width 11.61 ″Revs/Mile 621.5Circum. 102.0″
Tire 1
Specification
Tire 2
31.92"
Diameter
32.45"
12.4"
Width
11.61"
4.96"
Sidewall
5.23"
100.284"
Circum.
101.953"
631.8
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