How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.24%

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

-1.24%

Absolute Difference

-0.32"

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
3029.6-0.4
4039.5-0.5
5049.4-0.6
6059.3-0.7
7069.1-0.9
8079-1
Tire 1Dia. 25.72 ″Rim 18 ″3.86 ″Width 9.65 ″Revs/Mile 784.2Circum. 80.8″Tire 2Dia. 25.40 ″Rim 18 ″3.70 ″Width 9.25 ″Revs/Mile 794.0Circum. 79.8″
Tire 1
Specification
Tire 2
25.72"
Diameter
25.4"
9.65"
Width
9.25"
3.86"
Sidewall
3.7"
80.791"
Circum.
79.801"
784.2
Revs/Mile
794

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