How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-0.55%

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

-0.55%

Absolute Difference

-0.18"

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
2019.9-0.1
3029.8-0.2
4039.8-0.2
5049.7-0.3
6059.7-0.3
7069.6-0.4
8079.6-0.4
Tire 1Dia. 32.59 ″Rim 18 ″7.29 ″Width 11.22 ″Revs/Mile 618.9Circum. 102.4″Tire 2Dia. 32.41 ″Rim 18 ″7.20 ″Width 12.01 ″Revs/Mile 622.3Circum. 101.8″
Tire 1
Specification
Tire 2
32.59"
Diameter
32.41"
11.22"
Width
12.01"
7.29"
Sidewall
7.2"
102.374"
Circum.
101.817"
618.9
Revs/Mile
622.3

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