How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.14%

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

-1.14%

Absolute Difference

-0.3"

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
2019.8-0.2
3029.7-0.3
4039.5-0.5
5049.4-0.6
6059.3-0.7
7069.2-0.8
8079.1-0.9
Tire 1Dia. 26.30 ″Rim 15 ″5.65 ″Width 8.07 ″Revs/Mile 766.9Circum. 82.6″Tire 2Dia. 26.00 ″Rim 15 ″5.50 ″Width 8.46 ″Revs/Mile 775.6Circum. 81.7″
Tire 1
Specification
Tire 2
26.3"
Diameter
26"
8.07"
Width
8.46"
5.65"
Sidewall
5.5"
82.621"
Circum.
81.694"
766.9
Revs/Mile
775.6

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