How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.92%

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

-1.92%

Absolute Difference

-0.49"

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
2019.6-0.4
3029.4-0.6
4039.2-0.8
5049-1
6058.8-1.2
7068.7-1.3
8078.5-1.5
Tire 1Dia. 25.46 ″Rim 17 ″4.23 ″Width 8.46 ″Revs/Mile 792.0Circum. 80.0″Tire 2Dia. 24.97 ″Rim 17 ″3.99 ″Width 8.86 ″Revs/Mile 807.6Circum. 78.5″
Tire 1
Specification
Tire 2
25.46"
Diameter
24.97"
8.46"
Width
8.86"
4.23"
Sidewall
3.99"
79.999"
Circum.
78.453"
792
Revs/Mile
807.6

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