How it works

TireFlows

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

Tire 1
/R
Tire 2
/R

Result

Diameter Difference

-1.94%

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

-1.94%

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
2019.6-0.4
3029.4-0.6
4039.2-0.8
5049-1
6058.8-1.2
7068.6-1.4
8078.5-1.5
Tire 1Dia. 28.40 ″Rim 16 ″6.20 ″Width 8.86 ″Revs/Mile 710.1Circum. 89.2″Tire 2Dia. 27.85 ″Rim 16 ″5.93 ″Width 8.46 ″Revs/Mile 724.2Circum. 87.5″
Tire 1
Specification
Tire 2
28.4"
Diameter
27.85"
8.86"
Width
8.46"
6.2"
Sidewall
5.93"
89.226"
Circum.
87.495"
710.1
Revs/Mile
724.2

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