How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.51%

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

1.51%

Absolute Difference

0.49"

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
3030.5+0.5
4040.6+0.6
5050.8+0.8
6060.9+0.9
7071.1+1.1
8081.2+1.2
Tire 1Dia. 32.52 ″Rim 21 ″5.76 ″Width 12.80 ″Revs/Mile 620.3Circum. 102.2″Tire 2Dia. 33.01 ″Rim 21 ″6.00 ″Width 12.01 ″Revs/Mile 611.0Circum. 103.7″
Tire 1
Specification
Tire 2
32.52"
Diameter
33.01"
12.8"
Width
12.01"
5.76"
Sidewall
6"
102.151"
Circum.
103.697"
620.3
Revs/Mile
611

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