Car Tyres are going to get Taller and Thinner

Size and shape of car tyres will be changing

This is a good story for let’s say for the more mature garage owners amongst us, (the older guys). We are the ones that remember the cars and their car tyres back in the 1960’s and on from there. The tyre industry is about to do a turn around when it comes to car tyres design and sizes and will revert back to similar ones that were used in the early days, they are to start making taller and thinner car tyres.
This reversal has come about by pressure from governments to encourage car manufacturers to design and make their cars more ECO friendly. By reverting back to the tall thin tyre they are helping the car designers to reduce fuel consumption and help give their cars better carbon emissions figures.

When I first worked in the industry this type of tyre sizes were the norm.

The MGB sports car came out on 165×14 tyres a narrow tyre by today’s standards. The early E-Type Jaguars were originally fitted with 185v15 size tyres as were the Ferrari 250 GT’s. Even the more every day type of cars such as the VW Beetles and Volvos were fitted with 155×15 and 165×15 size tyres, which were very narrow compared with some of the tyre sizes that were later to be developed.

bridgestone ecopia tyre
Bridgestone tyre showing the tall and thin effect of the new car tyres.

Pirelli one of the companies to develop the slimmer car tyres.

Pirelli have said that they will be driven to come out with new sizes by stricter European Union regulations that will force them to develop tyres that have the best ratings. The idea of this is to reduce the rolling resistance of the tyres. The first target for the regulations is 2016 and then a higher target in 2020. The new tyre rules will be getting stricter and stricter, and so it will not be long before we see this type of tyre coming into our garages and tyre shops.

What is rolling resistance?

Rolling resistance is basically the friction between the wheel and tyre and the road surface. The broader the tyres footprint then the more resistance is created, we would normally put this down to a better grip and this is one of the reasons that the low profile tyres were developed, firstly for motorsport and then for road cars.
Also at the bottom of the tyre where the tyre meets the road surface, there is a flat spot, this is known as the “compact patch “and as you roll over it going forward the flat section moves round the tyre. The shape of the tyre is constantly changing.

This gives an extra resistive force.

This why the car uses more fuel when your tyres are not inflated correctly (under-inflated), the engine is having to work harder to push the car along with its flatter tyres.

A simpler way of putting it is that if you have a half flat tyre on your bicycle you know that it is much harder to peddle, then it is the same for your car, this is known as “rolling resistance”.
Also because of more modern tread designs, then there has been no loss of “wet and dry grip,” This is also due to more modern tyre compounds and treads patterns with deeper sipes.

Sipes are the tiny slits that help to dissipate the water in wet driving conditions. This tyre design is incorporated in Michelins new tyre the Michelin AS all season tyres, as the tyre wears down then the sipes do as well, giving excellent grip as the tyre wears down,

In fact Bridgestone and Michelin are two of the tyre companies that are involved in the development of the taller, thinner tyres.

In fact the new BMW i3 concept car has come out on 19 inch wheels, tyre size 155/70×19 but the tyres are half the width of the conventional

BMW 3 series cars, according to Michelin by increasing the tyres diameter by 2 inches will reduce rolling resistance by about 5%.
The new Citroen C4 cactus will use 18 inch wheels, which will be just 155mm wide (about 6 inches).
One good thing about this is that I love change? I believe that these new tyre designs are what makes our job more interesting, especially for us older guys who remember the original skinny tyres going back 40 or 50 years.