Tires: They Can Be The Achilles Heel of the Electric Vehicle
History of the term
Achilles was a hero in Greek mythology of the Trojan War who was believed to be invulnerable except for where Thetis had held him by the heel in the river Styx to make him immortal. Paris shot Achilles with an arrow in the heel and Achilles eventually died of his wounds.
I like to take my EV to car shows and other EV events explaining the virtues of electric vehicles. Someone will eventually ask “What is something that is worse on an electric vehicle than on a conventional vehicle?” This may sound blasphemous coming from me, but I always have to say the tires. Tires play a critical role in driving an electric vehicle and they have quite a few things going against them. The big difference will be the torque, mass, exotic sizes and rolling resistance. In some of the more high performance electric vehicles, such as a Tesla Model S P85+, driven hard, you can go through a set of tires in 8,000 to 12,000 miles. The tires on a P85+ are staggered 21 inch rim diameter. Staggered meaning the rear tires are wider in the rear than in the front which provides greater performance and launch grip, but cannot be rotated. Other vehicles, like the BMW i3 use a large diameter, but narrow tire to generate a performance size contact patch, where only Bridgestone and a few other manufacturers make the tire size for the vehicle. Even though it is easy to burn up a set of tires, driving and proper maintenance can prolong the life of your tires so that you can get 30,000 to 50,000 miles out of a set. As an EV owner, consider the tire choices available to you and be sure to maintain them to get maximum life out of your tires. To some this may not be an issue. If you have driven a heavy car or a performance car, you already know about tire wear, or if you already baby your tires, you probably will not notice much of a difference, but for many, this will be their first car that is heavier or has more performance than their prior vehicles.
Tires on an EV get to see extremes due to some of the features on an electric vehicle. Electric vehicles tend to weight about 20 to 30% more than their internal combustion counterparts mostly due to the batteries. They also deliver instant torque. Pushing that weight around and accelerating hard will play a factor on tire life. Try to avoid hard acceleration or pushing hard into a turn when it really isn’t necessary. Hard cornering and jack-rabbit starts will scrub the tread and make them wear more quickly. Take it easy when accelerating off the light and utilize apexing, (using the largest radius through a turn or starting at the outside of a turn, turn into the inside of the turn halfway and exit the turn as far to the outside as possible while going through a turn so there is less of a radius). Use regenerative braking to your advantage to slow the car as well. The motor will want as much of the energy returning to it rather than the tires and brakes which will help to smoothly slow you down.
Alignment, rotation and tire pressure also play an important part to prolonging the life of your tires. Make sure you are running at the recommended tire pressure for your vehicle. Check it weekly to make sure you are not running above or below the recommended pressure. Recommended tire pressure can usually be found on the door of your vehicle or in the manual. Note that changes in outside temperature can affect the tire pressure in your vehicle as well. Too high of a pressure will round out your tire and cause a rougher ride, reduce handling and wear to the center section tread. Too low of a pressure will wear the sides of the tread, create more road noise and sloppier feel going around turns. Note that if you checked your pressure when it was hot outside and the next time it is cold, your pressure will appear low and vice versa. Regular checking will keep the pressure and wear in check. Invest in a good analog tire gage with a bleeder valve so it is easier to regulate the tire pressure when you fill the tire. Simple 12 volt tire pumps make it easy to check and fill your air pressure wherever you go. Make sure the car’s wheel alignment is kept in check too. I would highly recommend a 4 wheel alignment at least every 6 months, but a year at the longest. If you have a performance EV have your alignment checked frequently or if you have hit a curb or hard pothole, I would also get it checked right away. EVs have a tendency to wear the inside edge of the tire, this is usually caused by a toe-in or negative camber situation. Make sure that when they have the car on the alignment rack that they are checking for this condition and have thoroughly checked the inside edge of the tread. It is very difficult to check this without being under the car. The tire can look completely normal but the inside edge will look like someone chamfered it off with a knife. Alignment will keep all the tires pointing in the same direction and help prolong wear. Tire rotation also helps increase the life of your tires. If you have a vehicle that has the same size tires on the front and rear, this is pretty easy. The front wheels can go to the rear and the rear to the front. This helps balance the wear patterns between these areas. If you have staggered wheel patterns, you cannot just move the wheels from the front to the rear, but you can have the tire removed from the rim on the left and exchanged with the tire on the right. Unmounting and remounting tires is usually expensive and may wind up costing more money than just replacing the tires when they eventually wear out. With whatever tire rotation pattern is used. Make sure that if a specific wheel rotation is noted on the sidewall of the tire that the tire rotates in that direction when rotated.
Lastly, inspect your tires for any punctures or damage. With the higher load and pressure placed on EV tires, they are less likely to resist a puncture. Visually inspect the tire for screws or nails and check the sidewalls regularly for any bubbles or gashes for rubbing or hitting a curb while driving or parking. Sometimes you can hear a nail or screw in your tire if you notice a clicking sound as the tire rotates. That is the head of the nail or screw making contact with the pavement. If you find any issues, have them inspected by a professional as soon as possible. Also the low tire pressure sensor is your friend, it can detect a flat by either sensing a pressure drop in a tire or noting a different RPM of one tire from the others. If your pressure sensor warning goes off, it usually means there is a problem, even if you haven’t noticed an issue or could even visually notice a change in tire pressure. Have it checked out immediately.
One of the big surprises EV owners and new car owners find out is that there their car does not come with a spare tire. If you don’t know if you have one or not, it’s probably a good idea to check now. Spare tires add extra weight and take up a lot of space in a car that is probably already challenged in one or both of those areas. You probably don’t have a jack or lug wrench in the car either. Depending on your comfort level with maintenance, you can carry a repair kit or pursue different options. If you have no interest in changing your own tire, make sure your vehicle comes with a roadside assistance program or you have the proper towing service through an auto club provider to get you to a preferred dealer or tire store. Since you have no spare, you will probably have to be towed out of the situation. Some tire stores also offer free tire patching, such as America’s Tire/Discount Tire regardless if you bought the tire from them (Their angle is that you probably need a new tire anyway and now they have you as a captive customer). If you are capable of doing simple maintenance, I highly recommend that you carry a tire repair kit in your car. This includes, tire goo/sealant, tire plugs, tire plug hole reaming and install tool, lug wrench, torch wrench, jack, regular and needle nose pliers, a knife or other cutting tool and a tire pump that can be run from the cigarette lighter (and has a cord and hose that can reach all 4 wheels). This should give you all the tools you need to repair a puncture on the side of the road and it will all fit within the space of a gym bag. This is more versatile than carrying a spare, but for some people, this is an ultimate solution. Provided the puncture is in a repairable area, usually within the tread lines before the edge tread pattern, you should be fine to plug it with a repair kit. The best repair is a patch that is installed by removing the tire from the rim and patch the tire from the inside. There is really no right answer for all situations, but find the solution that is correct for you so you are not surprised and scrambling when the time comes.
With all these recommendations, this should help with prolonging the life of your tires, but ultimately the tires on your electric vehicle will need to be replaced. This will probably be the most expensive maintenance item on your vehicle that will not be covered by a warranty, so do your due diligence. The tires you currently have may be somewhat exotic, either due to their size or their material or tread features that reduce tire noise or rolling resistance. Be prepared for a higher price than what you expect to pay for a conventional vehicle. Try to match the brand and model that you are currently using when researching new tires. Those tires meet the specification of your car. If you are going to select another brand, make sure that they have the same or exceed the load and wear rating of your current brand and model. You may find a cheaper tire with a lower load rating, but the weight of the vehicle will wear them out faster. A softer tire will also lead to more rolling resistance and while they may ride better, you can expect a 10 to 20% decrease in your range if you do not match the tire up carefully.
Your dealer will have the best match for your car, but also good tire shops and online retailers can provide you with the tires you need. Make sure that when you get a quote that they include the cost of the tire, delivery fees, installation labor, balance, tire stems, disposal fees and registration. Also check to see if any of the merchants offer perks like free road hazard, tire rotation and inspections. Find the deal that works for you. Know the general price and availability of your tires before its time to replace them. Although it may be impossible to get the dealer to match a tire shop price, you can usually get tire shops to compete for your business. You will be going through a lot once the tires need replacement and doing this homework in advance will save you a headache when the time comes.
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