Most of us buy tyres by looking at the price on the shelf. It’s the obvious thing to do, and it’s the wrong number.
A tyre has two costs. There’s what you pay for it, spread over however many miles it lasts. And there’s the fuel or electricity it burns when driving. A tyre that requires more force to roll (rolling resistance), costs you more at the pump over time.
On average, a set of premium tyres in a common 18-inch size can cost you roughly 2.3p per mile to buy.
The fuel to move the car they are fitted to can cost somewhere between 12p and 24p a mile, depending on what your car runs on.
Based on that, the fuel is five to ten times the tyre. And unlike the tyre's up front purchase price, you pay for your fuel weekly.
This means the cheapest tyre to run is not necessarily the cheapest tyre to buy - or even the longest-lasting one.
What Does Cost Per Mile Mean for Tyres?
There are two sides to the equation that need to be considered. Almost every comparison you’ll read online only does the first part.
The tyre half is the price of four tyres divided by the miles you get before they’re legally worn out.
The fuel half is the extra fuel a tyre burns because of its rolling resistance. And how much energy it takes to keep it turning.
No single tyre is responsible for your whole fuel bill. However, the difference between an efficient tyre and an inefficient one is a slice of a very large number.
Add them together and you get the real cost of a mile.
- Tyre cost per mile = (price per tyre x 4) / miles to the legal limit
- Fuel cost per mile = rolling resistance difference x fuel price
- Total cost per mile = tyre cost + fuel cost
When Do Tyres Reach the Legal Tread Limit? (1.6mm)
In the UK, a car tyre is illegal below 1.6mm of tread depth across the central three-quarters of the tread.
That’s Regulation 27 of the Road Vehicles (Construction and Use) Regulations 1986, confirmed in Annex 6 of the Highway Code.
If you are caught with a tread depth below this limit you face a £2,500 fine and three penalty points - per tyre.
New Tyre Tread Depth: How Much Rubber You Start With
Often it is stated that a new tyre comes with 8mm of tread - however, there's no reliable source for that number.
Michelin itself doesn’t provide one tread depth for its tyres, reflecting that it varies between ranges.
Tyre life isn’t only a function of new tyre tread depth, it also relates to other technologies that are employed, and the composition of the rubber affecting wear rate. Lower tread depths can also be a design choice in respect of providing improved handling, as tyre block movement is reduced.
The best measured figure comes from the European Commission’s Joint Research Centre. This put fifteen car tyres through the official on-road wear test and measured their starting tread at 7.5 to 7.7mm.
That same study found that summer tyres wearing at 1.47mm per 10,000km on the front axle and 0.64mm on the rear. Which meant that front tyres were wearing more than twice as fast as rears.
It also found that the tyres it tested ranged from 0.7 to 1.64 times the service life of the reference tyre.
In plain terms, the longest-lived tyre in that group lasted more than twice as long as the shortest.
What the Tyre Label Doesn't Tell You About Mileage
The tyre label grades fuel efficiency, wet grip and noise. This is a genuinely useful piece of information for buyers.
The European Commission states that the difference between adjacent fuel-efficiency grades is worth about 80 litres of fuel over the life of the tyre.
The government’s own Vehicle Certification Agency puts the spread between the best and worst grades at 7.5% of your fuel economy.
What this does not tell you is how long the tread will last. Which is why independent test data is need to fill the gap.