Let’s take another look at energy-saving tyres, pioneered by Michelin, and now offered by most major tyre suppliers.
They can now be identified on tyre labelling as tyres rated A or B for fuel economy, and the difference compared with an F-rated tyre could be as much as a six or seven per cent cost saving. You need to be fully aware of certain facts though, when you purchase a car, be it new or used, to take advantage of this fuel-saving technology. You need to know that most of the performance-oriented tyres (many rated F and G for fuel economy) tend to work in exactly the opposite direction, with construction technology, rubber mixes, and tread patterns that actually produce higher rolling resistance. It’s quite apparent that many innocent car buyers are tempted by the design and appearance of big alloy wheels fitted with high-performance low profile tyres, and the accompanying images of performance and fast driving that, arguably, are out of place on most public roads, and certainly out of place on family hatchbacks and MPVs. The car manufacturers often strongly promote such wheels and tyres – by offering them as standard equipment on relatively modest cars with no sporting pretensions, or as modestly priced options.
They can do this with the aid of price deals with tyre manufacturers that ensure the tyre people good profits when owners come to replace these uneconomical, and more expensive, tyres. It’s often difficult to avoid some of such deals, as the upgraded wheels and tyres come bundled with other options that may be quite desirable for reasons unrelated to performance. Buyers may find that, in order to have climate control, or front and rear parking sensors, the upgrade comes with 17-inch or 18-inch alloy wheels fitted with sporty low profile tyres – and often there aren’t even any fuel-saving tyres available in those sizes, when it comes to replace them. These tyres will use more fuel, most likely be noisier than the typical equivalent energy-saving size of 205/55/16, and cost around £30 to £40 more each to replace. Based on average tyre life of 25,000 miles, and a modest four per cent fuel saving using energy saving tyres, (just 2mpg in 50mpg) the eye-catching alloys and wide tyres cost an owner £250 more in fuel and replacement costs over 25,000 miles. Anyone tempted by the modest £300 extra for optional 18-inch rims, with their 235/40/18 tyres, had better budget for a further £100 in fuel costs and, with tyre replacement more frequent at 15 to 20,000 miles, an extra £150 to £300 over the same period for wear, along with a noticeably bumpier ride! There’s also a small, but significant, jump in aerodynamic resistance (and fuel costs) each time you step up a wheel and tyre size, and a probability that the under-floor boot well that will house a standard full-size 205/55/16 spare won’t take anything bigger, meaning it’s either a skinny space-saver spare wheel, or even worse, the dreaded puncture repair kit!
All things considered, it’s hard to save fuel by driving intelligently with the kind of handicap that these wide low-profile tyres impose. The downsides of energy-saving low rolling resistance tyres? Their wet grip used to be rather inferior, but the major manufacturers have now cracked the problem, and we’ve confirmed that they all offer tyres rated A or B for fuel efficiency, together with A or B for wet grip, and will offer significantly better grip than wider tyres in snow. Energy-saving tyres are also generally quieter and occasional assertions that they may give a harsher ride are questionable, since the fuel savings come mainly from the tread design and the formulation of the rubber used in the tread section, not from side-wall properties; try Bridgestone Ecopia tyres if you want economy tyres that ride really well, and quietly.
We must finally mention that rolling resistance of any new tyre reduces with mileage, as the tread depth is reduced by wear, and sets of new energy-saving tyres may not show immediate benefits; fuel economy calculations, from the car’s on-board-computer (OBC), or by brim-to-brim checks, will also be distorted by the larger circumference of new tyres. In fact you’ll be covering more miles compared with before than your instruments may declare, as wheel rotation count is the usual method of distance measurement. If you use your satellite navigation for the distance input, it is possible to produce more accurate results on longer trips.