Got a question? 1300 756 884

Retrieve quote

The Truth About Low Profile Tyres

‘Profile’ is the relationship between the width of the tyre – shoulder to shoulder – and its sidewall height – rim to tread. Profile is expressed as a percentage of height to width, so a 100 percent profile tyre, like a 7.00×16 bias-ply tyre from the ‘50s and ‘60s, has a sidewall height the same as its width.

 

Low Profile

 

You can tell the profile of a 4×4 tyre by looking at the code on the sidewall: the section width (in millimetres) is followed by a forward slash and the profile figure. Most new passenger-carrying 4x4s are delivered on 65, 70 or 75 profile tyres, so sidewall codes look typically like 275/70 or 235-75. However, new luxury 4x4s are delivered on 60 or even 55 profile tyres.

 

Why Lower the profile?

There are several main reasons why 4×4 makers are taking the low profile tyre path: more precise steering; better on-road handling; more powerful braking; quicker water dispersal; more torque capacity; and, of course, the fashionable ‘fat tyre look’.

 

Low profile tyres improve steering response because there’s a reduced amount of flexible sidewall between the wheel and the tyre tread. If you fitted a video camera to the front mudguard of a 4×4 and steered it around a series of hard turns you’d see how sidewall flex slows down the steering action that’s imparted to the wheel.

 

Low Profile 2

 

With a higher-profile tyre the wheel can be seen moving momentarily before the tyre follows it. With a low profile tyre there’s no perceptible tyre sidewall flex on the wheel and tyre carcass moves as one in response to steering inputs.

 

A low profile tyre can improve on-road handling, because the stiffer sidewall doesn’t roll towards the inside of the corner and so the tread area remains more stable, in contact with the road.

 

As the on-road performance of 4x4s continues to increase, the need for more powerful brakes rises in proportion. We saw a shift in the 1990s across the entire 4×4 large wagon market from 15-inch to at least 16-inch wheels and the main driver for that move was the need to fit bigger-diameter brake discs. As power levels and braking demands climb higher the shift from 17x to 18s, 19s and even 20-inch wheels has begun.

 

The torque load on a tyre is greatest at lift-off and under heavy braking, and the torque capacity of a tyre is generally increased if its sidewalls aren’t very tall. A stiffer sidewall is better able to resist the tendency for a wheel to rotate inside the tyre – look at slow-mo footage of a dragster taking off for an illustration of tyre torque capacity.

 

For more information about low profiles call 1300 COOPER and talk to one of our specialists.

Related categories

Live chat with us now