How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

0.7%

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

0.7%

Absolute Difference

0.21"

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
2020.1+0.1
3030.2+0.2
4040.3+0.3
5050.4+0.4
6060.4+0.4
7070.5+0.5
8080.6+0.6
Tire 1Dia. 29.83 ″Rim 19 ″5.41 ″Width 10.83 ″Revs/Mile 676.2Circum. 93.7″Tire 2Dia. 30.04 ″Rim 19 ″5.52 ″Width 10.04 ″Revs/Mile 671.3Circum. 94.4″
Tire 1
Specification
Tire 2
29.83"
Diameter
30.04"
10.83"
Width
10.04"
5.41"
Sidewall
5.52"
93.704"
Circum.
94.384"
676.2
Revs/Mile
671.3

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