How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.37%

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

2.37%

Absolute Difference

0.61"

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
2020.5+0.5
3030.7+0.7
4040.9+0.9
5051.2+1.2
6061.4+1.4
7071.7+1.7
8081.9+1.9
Tire 1Dia. 25.72 ″Rim 18 ″3.86 ″Width 9.65 ″Revs/Mile 784.2Circum. 80.8″Tire 2Dia. 26.33 ″Rim 18 ″4.16 ″Width 9.25 ″Revs/Mile 766.1Circum. 82.7″
Tire 1
Specification
Tire 2
25.72"
Diameter
26.33"
9.65"
Width
9.25"
3.86"
Sidewall
4.16"
80.791"
Circum.
82.708"
784.2
Revs/Mile
766.1

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