How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.75%

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

1.75%

Absolute Difference

0.57"

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
4040.7+0.7
5050.9+0.9
6061+1
7071.2+1.2
8081.4+1.4
Tire 1Dia. 32.59 ″Rim 18 ″7.29 ″Width 11.22 ″Revs/Mile 618.9Circum. 102.4″Tire 2Dia. 33.16 ″Rim 18 ″7.58 ″Width 10.83 ″Revs/Mile 608.3Circum. 104.2″
Tire 1
Specification
Tire 2
32.59"
Diameter
33.16"
11.22"
Width
10.83"
7.29"
Sidewall
7.58"
102.374"
Circum.
104.167"
618.9
Revs/Mile
608.3

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