How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.41%

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

1.41%

Absolute Difference

0.43"

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
4040.6+0.6
5050.7+0.7
6060.8+0.8
7071+1
8081.1+1.1
Tire 1Dia. 30.48 ″Rim 19 ″5.74 ″Width 10.43 ″Revs/Mile 661.8Circum. 95.7″Tire 2Dia. 30.91 ″Rim 19 ″5.95 ″Width 10.83 ″Revs/Mile 652.5Circum. 97.1″
Tire 1
Specification
Tire 2
30.48"
Diameter
30.91"
10.43"
Width
10.83"
5.74"
Sidewall
5.95"
95.744"
Circum.
97.105"
661.8
Revs/Mile
652.5

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