How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

1.68%

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

1.68%

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. 32.71 ″Rim 17 ″7.85 ″Width 11.22 ″Revs/Mile 616.6Circum. 102.8″Tire 2Dia. 33.26 ″Rim 17 ″8.13 ″Width 11.61 ″Revs/Mile 606.4Circum. 104.5″
Tire 1
Specification
Tire 2
32.71"
Diameter
33.26"
11.22"
Width
11.61"
7.85"
Sidewall
8.13"
102.757"
Circum.
104.489"
616.6
Revs/Mile
606.4

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