With new EC tyre labelling regulations now in force, there’s far more information available to evaluate the potential benefits of low rolling resistance economy tyres, and also make other related observations regarding motoring costs, though the ratings aren’t actually marked on the tyre.
We can also now judge whether, as was the case in the past, gains in fuel economy with some low rolling resistance tyres come at the expense of poor wet road grip – a compromise that might well not be worth making in the interests of safety.
Less friction at the tyre and road interface can save energy, but mean reduced road grip; replacing the traditional carbon black with ground silica in rubber mixes improves wet road grip, whilst achieving good energy savings elsewhere by reducing the heat generated by flexing of the sidewalls and carcass.
Consequently, some energy-saving tyres do ride a little more firmly than standard tyres, but the differences are rarely too evident on most cars. Most premium tyre manufacturers now offer tyres that combine excellent fuel economy with good wet grip, and a few pounds extra spent on buying such quality tyres could well be worth a lot more than a few gallons of fuel in an emergency stop situation on a wet road. What scale of fuel savings can we expect to see with energy-saving tyres?
Based on rolling resistance effectively consuming 20 per cent of the fuel, tyres with an A rating for fuel economy should typically use 7.5 per cent less fuel than cars fitted with high rolling resistance G rated tyres, which sounds very encouraging; but, since there are no A or G rated tyres actually available at present, it takes the difference down to a realistic five to six per cent maximum potential economy benefit, when widely available B rated tyres replace F rated ones.
Such figures have been confirmed in independent tests by Which? magazine, and could mean a saving of around £65 to £75 a year, or more, in a 10,000 mile per year, based on 45 to 50mpg motoring. But these figures are both based on a typical motoring mix, and average driving style; arguably the potential gains are proportionately greater when you already drive economically, as the rolling resistance is then a more significant proportion of overall energy and fuel usage, although inevitably urban motorists will see lesser gains.
At one time “economy” tyres were significantly more costly than standard tyres, as some still are – but now it’s no more than £5 to £10 a tyre in most sizes, or £20 to £40 a set. That would knock the fuel savings back by around 20 per cent, based on 30,000 mile tyres life, but some low energy tyres are particularly hard wearing, which may more than recover any added purchase costs. Refer to owner reports, web sites such as www.tyrereviews.co.uk , www.tyretest.com and Which? magazine for comparative tests and wear ratings, bearing in mind that how you drive, and how well you maintain your tyre pressures and steering geometry, are as important as tyre quality.
Contrary to some expectations, wet grip ratings show that low profile tyres compare well with smaller and narrower tyres, although possibly they may not bite through slush and snow quite as well. Neither do bigger and wider tyres necessarily have a higher rolling resistance than more modest tyres. But they are undeniably significantly more expensive to replace, with costs jumping from £65 to £80 per tyre for a 195/65/15 to £120 to £150 for a 225/45/17 tyre on big alloy wheels that might be offered as an optional alternative; such expense can blow away the efforts of many miles of economical motoring!
Choosing car model variants that come with sensibly sized standard tyres, and possibly “economy” tyres, should be part of your new car buying experience, if motoring costs are important to you, and the same thing applies when you’re replacing worn tyres. If you are keenly aware of your fuel economy, you may well notice a significant difference in your fuel costs if you buy badly and fit high rolling resistance tyres in ignorance of the downside.