How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.5%

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

1.5%

Absolute Difference

0.38"

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
2020.3+0.3
3030.5+0.5
4040.6+0.6
5050.8+0.8
6060.9+0.9
7071.1+1.1
8081.2+1.2
Tire 1Dia. 25.31 ″Rim 16 ″4.66 ″Width 8.46 ″Revs/Mile 796.8Circum. 79.5″Tire 2Dia. 25.69 ″Rim 16 ″4.84 ″Width 8.07 ″Revs/Mile 785.2Circum. 80.7″
Tire 1
Specification
Tire 2
25.31"
Diameter
25.69"
8.46"
Width
8.07"
4.66"
Sidewall
4.84"
79.517"
Circum.
80.692"
796.8
Revs/Mile
785.2

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