How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.08%

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

2.08%

Absolute Difference

0.51"

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
2020.4+0.4
3030.6+0.6
4040.8+0.8
5051+1
6061.3+1.3
7071.5+1.5
8081.7+1.7
Tire 1Dia. 24.47 ″Rim 15 ″4.73 ″Width 7.28 ″Revs/Mile 824.2Circum. 76.9″Tire 2Dia. 24.98 ″Rim 15 ″4.99 ″Width 7.68 ″Revs/Mile 807.4Circum. 78.5″
Tire 1
Specification
Tire 2
24.47"
Diameter
24.98"
7.28"
Width
7.68"
4.73"
Sidewall
4.99"
76.87"
Circum.
78.478"
824.2
Revs/Mile
807.4

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