How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-0.4%

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

-0.4%

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
2019.9-0.1
3029.9-0.1
4039.8-0.2
5049.8-0.2
6059.8-0.2
7069.7-0.3
8079.7-0.3
Tire 1Dia. 25.31 ″Rim 16 ″4.66 ″Width 8.46 ″Revs/Mile 796.8Circum. 79.5″Tire 2Dia. 25.21 ″Rim 16 ″4.61 ″Width 7.68 ″Revs/Mile 799.9Circum. 79.2″
Tire 1
Specification
Tire 2
25.31"
Diameter
25.21"
8.46"
Width
7.68"
4.66"
Sidewall
4.61"
79.517"
Circum.
79.208"
796.8
Revs/Mile
799.9

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