What you need to know about tires for your hybrid or EV
When shopping for new tires, most of us simply check the tire size before going online or calling up our favourite rubber shop. But with many EVs and hybrids, there are a few numbers to check out besides the size.
In case you needed a refresher, tire sizes are embossed on the side wall. They usually start with a P on passenger cars, or LT on trucks. The next three numbers indicate the width of the tire tread in millimetres, the next two the side wall’s height as a percentage of the width, and the final two the wheel size in inches. A P225/65R17 tire, for instance, is 225 mm wide, the side wall is 65 per cent of the tire’s width, and the wheel size is 17 inches.
Just after that, you’ll find another two or three numbers, followed by a letter. These denote the tire’s load-carrying ability and speed rating, respectively. These numbers should also be duplicated on the label affixed to the driver’s side door frame, which also lists recommended air pressure.
When checking out new boots for EVs and hybrids, the load rating can be just as important as the overall size, because battery packs represent a substantial portion of their total weight. Never opt for a load rating that’s lower than original specs.
With the increasing number of EVs and hybrids on the road, manufacturers and drivers alike are looking for another two specs that you won’t find on any tire side wall or in catalogue details — grip rating and rolling resistance. Grip performance might not always be top-ofmind, but because electric motors can deliver maximum torque almost instantly, having tires that won’t spin out can be crucial. The problem is that most tires designed to deliver maximum grip are usually made of softer rubber compounds than traditional tires. These seldom deliver the lifespan that most consumers expect.
The second problem is rolling resistance. As you may know, the more power it takes to roll a tire, the quicker your battery charge will dissipate, and softer compound tires use up more energy than their stiffer cousins. It’s unlikely this will make any appreciable difference in range unless you opt for a very aggressive off-road tire, which few EV owners would.
There is one way to avoid the quandary of needing both grip and long-life: adjust your driving style. Taking it easy on the accelerator will bring more range from both the battery pack and the tire lifespan. On top of saving money, you could also avoid a collision, because when the front tires are spinning without grip, they also remove steering control.