How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.34%

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

1.34%

Absolute Difference

0.39"

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
3030.4+0.4
4040.5+0.5
5050.7+0.7
6060.8+0.8
7070.9+0.9
8081.1+1.1
Tire 1Dia. 29.04 ″Rim 19 ″5.02 ″Width 10.04 ″Revs/Mile 694.5Circum. 91.2″Tire 2Dia. 29.43 ″Rim 19 ″5.22 ″Width 10.43 ″Revs/Mile 685.2Circum. 92.5″
Tire 1
Specification
Tire 2
29.04"
Diameter
29.43"
10.04"
Width
10.43"
5.02"
Sidewall
5.22"
91.23"
Circum.
92.467"
694.5
Revs/Mile
685.2

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