Rough rider

Date:26 March 2012 Tags:,

Nearly every new car seems to offer low-profile tyres. I like the look, but I’ve heard complaints about jarring rides, frequent blowouts, rim damage, and greater wear at lower mileage. Should I avoid them?

Low-profile tyres do seem to be popping up on a lot more cars these days, but they’re being offered for several reasons. Bigger wheels and skinnier sidewalls in a normal-sized wheel well mean manufacturers can make room inside the wheel for larger brakes. Thin sidewalls are also stiffer and deliver better cornering and road feel. Let’s not avoid the obvious though – low-profile tyres just look cooler than regular equivalents.

When we say low-profile, we’re talking about the size of the edge of the tyre. Read the numbers moulded into the sidewall; the second number printed in the series is the aspect ratio, indicating sidewall thickness as a percentage of tread width. For example, a P225/45R15 tyre has a 15-inch wheel size with 225 mm of tread width, and the sidewall is 45 per cent of tread width, or 101 mm. The higher the aspect ratio, the thicker the sidewall and the comfier the ride; lower aspect ratios lead to thinner sidewalls and a stiffer ride.

There are drawbacks to this kind of rubber. Tyres are a part of your car’s suspension – the sidewalls absorb some of the most vicious road imperfections. Unless the suspension has been designed to accommodate the stiffer sidewalls, it can mean a rougher ride. Blowouts (a hole in the tyre caused by road debris) shouldn’t be more frequent than with normal tyres since the tread and ply construction aren’t much different. Rapid deflation is something to be concerned about; hitting a pothole with thin sidewalls can damage the wheel. Tyre-makers constantly improve designs with more robust materials and construction, so newer tyres aren’t damaged as often as old low-profile tyres.

If you’re buying a new car for comfort, order smaller wheels fitted with larger-sidewall tyres – they’ll offer a softer ride. Less aggressive shocks may help a bit but at the cost of handling. Beyond this, you’re looking at changes to suspension hardware, which isn’t for the faint of heart. You’ll have a tough time finding parts anyway, as the aftermarket usually aims to make cars more rigid rather than pillow soft.

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