How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.95%

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

2.95%

Absolute Difference

0.75"

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
2020.6+0.6
3030.9+0.9
4041.2+1.2
5051.5+1.5
6061.8+1.8
7072.1+2.1
8082.4+2.4
Tire 1Dia. 25.46 ″Rim 17 ″4.23 ″Width 8.46 ″Revs/Mile 792.0Circum. 80.0″Tire 2Dia. 26.21 ″Rim 17 ″4.61 ″Width 7.68 ″Revs/Mile 769.4Circum. 82.3″
Tire 1
Specification
Tire 2
25.46"
Diameter
26.21"
8.46"
Width
7.68"
4.23"
Sidewall
4.61"
79.999"
Circum.
82.349"
792
Revs/Mile
769.4

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