Gavin Shoebridge – an electric vehicle nut, a keen environmentalist

                Electric Car Conversion Blog By Gavin Shoebridge

March 9th, 2010 at 7:31 pm

Low Rolling Resistance Tires – Are They Worth it?

Low Rolling Resistance Tire

Low Rolling Resistance Tire

Low Rolling Resistances Tires are designed to increase your car’s economy by reducing the amount of tire friction or resistance while driving. This means your engine or electric motor & batteries don’t have to break into a sweat just cruising down the road. In some cases the energy savings can be noticable, with up to 15% of the gasoline consumed by a typical car due to rolling resistance.

After reading that, buying a set of LRR tires for an electric vehicle sounds like a no brainer, but I recommend taking all things into consideration first, such as cost and lifespan. Depending on how much of your driving is at high speed (50+ mph) these “Tires of the Gods” may not be so heavenly after all.

For example, the differences many drivers have mentioned in the real world have been around the 2 miles-per-gallon mark. If the average set of a new set (four) of LRR tires cost $500, then it would take some time to pay itself off.

    To give you an idea, let’s look at two simplified examples, both driving 30 miles per day:

Car 1 has normal tires and travels 30 miles per day at 0.3 kWh per mile, which equals 9 kWh per day. If 9 kWh per day costs $0.16 per kWh, then that’s $1.44 per day in electricity.

Car 2 has LRR tires and also travels 30 miles per day at 0.27 kWh per mile, which equals 8.1 kWh per day. If 9 kWh per day costs $0.16 per kWh, then that’s $1.30 per day in electricity.

As you can see, I’ve given “Car 2″ an improvement in economy by 10%, which has saved the driver $0.14 cents a day in electricity. This means the tires would have to last 9.7 years (or 107,000 miles) before they’d pay themselves off in saved electricity costs.
When used in a gasoline powered car however you could expect a faster payback, though this is only due to the fact that gasoline cars are inherently inneficient and use much more money in fuel per-mile than an electric vehicle.

Another option for those on a budget is to find older, used tires with a hardened tread. This harder tread doesn’t flex and heat up (losing energy as heat) as much as newer, softer rubber. The gains would be minimal in a typical electric commuter vehicle as shown, but may help with a longer range electric vehicle or gasoline vehicle.

If you have a long range electric vehicle, and if you drive long distances regularly then the benefits of installing LRR tires are there. For Jo or Joanne Average who drive small, local-range electric cars I suggest to stick to their usual budget brand.

If you’re buying new LRR tires then you should be aware of their reputation for having less grip in wet conditions due to their harder tread, and/or higher required tire pressure. Keep this in mind if you live in a wet area and ask your supplier for statistics on the particular tire you’re interested in.

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