How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

2.55%

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

2.55%

Absolute Difference

0.67"

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
2020.5+0.5
3030.8+0.8
4041+1
5051.3+1.3
6061.5+1.5
7071.8+1.8
8082+2
Tire 1Dia. 26.31 ″Rim 17 ″4.66 ″Width 8.46 ″Revs/Mile 766.5Circum. 82.7″Tire 2Dia. 26.98 ″Rim 17 ″4.99 ″Width 7.68 ″Revs/Mile 747.5Circum. 84.8″
Tire 1
Specification
Tire 2
26.31"
Diameter
26.98"
8.46"
Width
7.68"
4.66"
Sidewall
4.99"
82.659"
Circum.
84.761"
766.5
Revs/Mile
747.5

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