Tires, Speed Ratings: Notes
The speed rating (e.g.: "T") behind the tire size specification (e.g.: 185/65 R 14 86T) indicates the maximum permissible speed (vmax ) for the tire.
When selecting the tires for a vehicle, ensure that their maximal permissible speed lies above the maximum speed attainable by the vehicle ("design-related").
Vehicles with National Type Approval
For all vehicles with national type approval, the maximum speed is calculated using the following formula:
Formula for Vehicles with vmax up to 150 km/h
vmax = 1.03 x v + 3.5 km/h SPEED RATING CODE .
Example: Indicated maximum speed v = 145 km/h.
vmax = 1.03 x 145 km/h + 3.5 km/h = 152.85 km/h.
In this example, a "Q" tire or a tire with a higher-order speed rating must be used.
Formula for Vehicles with vmax from 151 km/h
vmax = 1.01 x v + 6.5 km/h SPEED RATING CODE .
Example: Indicated maximum speed v = 163 km/h.
vmax = 1.01 x 163 km/h + 6.5 km/h = 171.13 km/h.
In this example, an "S" tire or a tire with a higher-order speed rating must be used.
Vehicles with EU Type Approval
For all vehicles with EU-registration, the maximum speed is calculated using the following formula:
vmax = 1.05 x v SPEED RATING CODE .
Example: Indicated maximum speed v = 172 km/h.
vmax = 1.05 x 172 km/h = 180.60 km/h.
In this example, a "T" tire or a tire with a higher-order speed rating must be used.
Using tires with a higher-order speed rating is permitted. The same applies for tires with higher-order load-carrying capacity characteristic number (load index).