How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.89%

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

-1.89%

Absolute Difference

-0.52"

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
2019.6-0.4
3029.4-0.6
4039.2-0.8
5049.1-0.9
6058.9-1.1
7068.7-1.3
8078.5-1.5
Tire 1Dia. 27.52 ″Rim 16 ″5.76 ″Width 8.86 ″Revs/Mile 733.0Circum. 86.4″Tire 2Dia. 27.00 ″Rim 16 ″5.50 ″Width 8.46 ″Revs/Mile 746.9Circum. 84.8″
Tire 1
Specification
Tire 2
27.52"
Diameter
27"
8.86"
Width
8.46"
5.76"
Sidewall
5.5"
86.443"
Circum.
84.835"
733
Revs/Mile
746.9

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