Tyres: The path of least resistance

Date: Friday, April 19, 2024 | Author: Alan Anderson

Rolling resistance for optimum fuel economy and battery life is becoming as important to vehicle manufacturers as wet weather grip and comfort.

According to Bridgestone, choosing the right van tyres can save operators almost £2,000 per vehicle. Investigating the impact of the company’s new Duravis Van tyres on carbon emissions and cost savings, a Comparative Study by Warwick Business School last August (for Bridgestone) reports that tyres with the least rolling resistance cut emissions and fuel wastage dramatically.

A recent 2021 study by the European Tyre & Rubber Manufacturers Association (ETRMA) showed that more than 505 LCVs ran on tyres with a fuel economy grade of E or higher and a Wet Grip Index of C or higher (i.e. poorer). Bridgestone claims that 95.85 litres of petrol could be saved per van every year with its advanced Duravis Van tyre, which is classified EU label Grade B for rolling resistance, compared to a rival ‘D’ rated alternative, further equating to savings of 80.79 litres for diesel and 373.12 kWh per year for EV vans.

Because its new tyre also offers greater longevity than Grade D alternatives and delivers a claimed 21% improvement in rolling resistance over its predecessor, the Duravis R660 – the new Duravis Van reduces costs through fewer annual replacements. For a five-van fleet, overall savings are projected to amount to around £895 per year and for a fleet of 100, the figure extrapolates to £17,900, says the tyre maker, and compensates 98% of its higher cost (£147.29) against a D-rated alternative (£101.65), according to Asda prices.

“You can certainly say that rolling resistance is becoming increasingly important and a big priority in the design stage, as more and more LCV fleets and van drivers are more conscious about the issue than ever before, owing to the challenging economic times we’re all navigating our way through,” Brett Emerson, Bridgestone consumer sales director, told What Van?.

Continental’s EcoContact is favoured as an OE (original equipment) fit by Volkswagen for its ID. Buzz Cargo because, being a Grade A tyre, it has one of the lowest rolling resistances on the market. However, the company’s general manager Steve Howat admits: “It’s a conflict between what drivers want and what vehicle manufacturers want,” and he questions whether EV operators will stick to recommended EV tyres come replacement time. For example, Continental also markets a more conventional VanContact Ultra alternative, which carries a B rating.

Operators should look further than simply shelf prices when choosing replacement tyres, especially with EVs where rolling resistance plays a notable role in battery drainage and ultimate service life. But while tyres are difficult to compare like-for-like as they have grown in size and performance over the decades, clearly today they represent much better value for money. As an example, a typical 5.20 size cross-ply tyre (as fitted to many 1970s CDVs) cost around £6 back in 1970 – almost £78 in today’s spending terms. Fast forward to 1980 and a typical best brand 165 x13 radial tyre was ticketed at £36 (£147). In contrast, a search on the web unearths the much grippier 195/65 x17 Transit-sized tyre on offer for under £70, with a fair number of quality budget brands cheaper still.

With an estimated 700 different names on the market, the price-conscious budget sector is steadily growing in popularity, according to Tyrepress, which publishes Tyres & Accessories magazine. If some of the weird and wonderful names, none sillier than Triangle, concern you, bear in mind that a good number of lower tier tyres also have some household names backing them. For example, Michelin also markets Polish-made Kormanan and Tigar brands – the latter originating from Siberia – as well as Kleber. Bridgestone boasts Firestone together with its long-serving mid-range subsidiary Dayton brand in its armoury, while under the Continental umbrella come the Semprit and Uniroyal names.

The relative affordability of new tyres should put paid to anyone considering second-hand alternatives. Aside from their uncertain history and treatment, plus the chance of a mismatch of makes on the same axle, their value for money in terms of life left is debatable. Also, there’s the chance that you may be swapping for an older tyre. While not illegal, as their performance reduces over time, even when not in use, it’s generally recommended, no matter how good they visually appear, that tyres should be replaced after 10 years.

You can gauge a tyre’s age by the code on the sidewall, which stipulates the week and year of manufacture. For example, ’23/19’ signifies the tyre was made in the 23rd week of 2019. Even if a used tyre is within the age limit, insurance may become an issue, warns First Vehicle Leasing. “The allure of saving money with second-hand tyres is understandable, but the risks and legal implications far outweigh the potential benefits. In the event of an accident, if it’s discovered that your tyres were not compliant (or the wrong type for an LCV), your insurance company could refuse to pay out, leaving you with a hefty bill for damages and liabilities.”

Choosing the right tyre can be difficult. One useful aid is WhatTyre’s unique tyre comparison engine. With a database of over 300,000 tyres it compares tyre label data with thousands of impartial third-party magazine tyre tests as well as OE and ESG (Environmental, Social, and Governance) details, helping consumers to choose a tyre based on what it does rather than just what it costs.

Pot luck

Britain’s deteriorating road surfaces have plagued drivers for too many years and took even more of a toll in 2023. Between them, the RAC and AA were called out to a staggering 600,000 tyre-related breakdowns last year, it’s claimed.

And it’s going to get worse. Almost one fifth (18%) of the UK road network – representing 37,000 miles – is assessed as having less than five years’ structural life remaining, with the average frequency of resurfacing for all classes of roads now standing at once every 116 years.

According to Kwik-Fit, this has cost fleet operators and private motorists combined close to £2bn in repairs and its research shows that over the past 12 months 59% of drivers hit an average of 11 potholes per month. Damage to tyres accounts for 50% of repairs, followed by wheel damage and suspension (both 29%) and steering (18%).

“If wheels are knocked slightly out of alignment it can compromise handling and cause uneven tyre wear but it may take time for this to become obvious,” warns Kwik-Fit. “What’s more with vehicles becoming increasingly technologically advanced, it’s also important to consider how road irregularities can affect features like advanced driving assistance systems (ADAS). Even the slightest misalignment in a vehicle’s steering can impact how the system interacts with the ADAS technology and can cause features such as lane assist to operate incorrectly, with the potential to bring significant safety ramifications,” it adds.

Electric LCVs, which are heavier than ICE equivalents, are becoming more popular. The weight of the battery required to power an EV puts more strain on the suspension system compared with a traditional engine. Not only does this leave EVs more susceptible to damage from road irregularities, it can also cause chassis components to wear out more quickly. Bridgestone says the sidewall on its new Duravis Van tyre can combat a degree of damage courtesy of its innovative Sidewall Protector Rib. Continental claims it is constantly monitoring the situation and its VanContact Ultra tyre has special sidewall blocks to resist kerb and pothole damage, although no tyre can withstand heavy impacts unless the compound mix is dramatically changed.

One solution may be the new airless tyres being developed by Michelin in conjunction with General Motors but irrespective of what tyres you run on, they all need regular checking. According to TyreSafe, the UK tyre safety organisation, a lack of knowledge and understanding about the danger of driving on defective tyres is worrying. Over six million tyres in the UK are found to have illegal tread each year, risking fines of up to £2,500 per tyre and three penalty points (source: TyreSafe Tread Depth Survey 2023); more than two million MOT failures occur each year due to tyre defects, with one million classified as dangerous, and one in five vehicle breakdowns on motorways and A roads are due to tyre defects (Source: National Highways).

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