How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.01%

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

2.01%

Absolute Difference

0.65"

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
6061.2+1.2
7071.4+1.4
8081.6+1.6
Tire 1Dia. 32.34 ″Rim 20 ″6.17 ″Width 11.22 ″Revs/Mile 623.6Circum. 101.6″Tire 2Dia. 32.99 ″Rim 20 ″6.50 ″Width 10.83 ″Revs/Mile 611.3Circum. 103.6″
Tire 1
Specification
Tire 2
32.34"
Diameter
32.99"
11.22"
Width
10.83"
6.17"
Sidewall
6.5"
101.607"
Circum.
103.648"
623.6
Revs/Mile
611.3

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