How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

0.39%

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

0.39%

Absolute Difference

0.1"

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
2020.1+0.1
3030.1+0.1
4040.2+0.2
5050.2+0.2
6060.2+0.2
7070.3+0.3
8080.3+0.3
Tire 1Dia. 25.97 ″Rim 18 ″3.99 ″Width 8.86 ″Revs/Mile 776.5Circum. 81.6″Tire 2Dia. 26.07 ″Rim 18 ″4.04 ″Width 8.07 ″Revs/Mile 773.6Circum. 81.9″
Tire 1
Specification
Tire 2
25.97"
Diameter
26.07"
8.86"
Width
8.07"
3.99"
Sidewall
4.04"
81.595"
Circum.
81.904"
776.5
Revs/Mile
773.6

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