Batteries are heavy – so electric or hybrid vehicles weigh more than their conventional counterparts and this places additional stresses on the tyres, especially where sports cars are concerned.
At the same time, these heavier models offer little scope for fitting larger tyres with higher load capacities. In response, Continental is now manufacturing the first passenger tyre with the new ‘HL’ load index code.
Inflated to the same pressure, these tyres have a higher load capacity than those built to the former XL standard. On the sidewall, products with the new maximum load capacity display the HL code ahead of the size, as in ‘HL 245/40 R 19 101 Y XL’.
The load capacity of this HL tyre stands at 825 kg (load index 101), which equates to a 10% increase over the familiar XL standard of 750 kg (load index 98).
Passenger tyres of this size built to the SL standard, adequate for many cars, up to and including mid-range models, can take a maximum load of 670 kg (load index 94). That makes the load capacity of the new HL tyres almost one quarter higher.
Looking ahead, Continental is expecting to see growing demand from vehicle manufacturers for tyres with the new HL code.
Increasing the load capacity while at the same time meeting customer requirements called for a number of changes in both the tyre structure and the rubber compound.
“We were dealing here with tradeoffs that needed resolving at a very high level,” says Dr Stefan Habicht who was in charge of the development project for these tyres.
“In terms of construction, we reinforced the bead and enhanced the contour of the tyre to reduce tyre/road noise. At the same time, we also optimised the pattern compound. As a result, we were able to achieve low rolling resistance, ensure precise handling and keep mileage at its customary high level.”
Continental is currently producing the first tyres to the new HL standard for original equipment (OE) fitments, but they will also be available in the replacement market. Currently the HL tyre range is manufactured at Contintental’s plant in Otrokovice in the Czech Republic, and is marketed around the globe.