How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.66%

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

1.66%

Absolute Difference

0.55"

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
5050.8+0.8
6061+1
7071.2+1.2
8081.3+1.3
Tire 1Dia. 33.16 ″Rim 18 ″7.58 ″Width 10.83 ″Revs/Mile 608.3Circum. 104.2″Tire 2Dia. 33.71 ″Rim 18 ″7.85 ″Width 11.22 ″Revs/Mile 598.3Circum. 105.9″
Tire 1
Specification
Tire 2
33.16"
Diameter
33.71"
10.83"
Width
11.22"
7.58"
Sidewall
7.85"
104.167"
Circum.
105.899"
608.3
Revs/Mile
598.3

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