At a press event several years ago I had a pleasant chat with the UK marketing director of a certain car company. Despite his title, he was German, and he expressed amazement at the British enthusiasm for choosing large wheels and low-profile tyres from the options list.
This was much less common in his home country, where, he told me, wheel sizes are on average at least an inch smaller than they are here.
Not that he was complaining about it. There’s a lot of profit in persuading people to pick the large-wheel option. It usually adds several hundred pounds to the price, in some cases a few thousand, and you can bet your life that the manufacturers are paying the wheel and tyre makers only a small fraction of that.
The usual reason for upgrading to larger wheels is that they look better than small ones. If that appeals to you, and you’re prepared to spend money on achieving it, fair enough.
But there are a few problems. For a start, there’s a greater risk of damaging a larger wheel against a kerb. They’re also more expensive to replace. Most of all, they frequently make the car much less pleasant to drive.
This isn’t always true. Back in 1997, Subaru sold a car called the Impreza Sport. The only technical difference between the Sport and the GL was that the Sport’s wheels were one inch larger.
You might not think this would make much difference, but it did. The GL was a pleasant car to drive. The Sport was glorious. That small change in wheel size sharpened up the handling almost unbelievably.
More commonly, though, the optional wheels and tyres make little difference to the handling and have a devastating effect on the ride quality.
It’s not the wheels themselves that cause this. It’s the fact that you have to fit lower-profile tyres to them so that the circumference remains the same. If you didn’t, there would be space issues and the gearing would go to pot.
Lower-profile tyres have smaller sidewalls (the sidewall being the part of the tyre you can see around the wheel when you’re looking at it side-on). Since there is less rubber, it can’t be deformed as easily, so shocks which would otherwise be absorbed by it are passed through to the suspension instead.
Suspension is set up to deal with a particular wheel/tyre size. If you change this, the suspension is no longer able to cope as well as it did before. It does not damp the shocks coming from the road as effectively, so those shocks are transferred to the rest of the car and, ultimately, to you.
This is noticeable in all cars, but in some more than others. The first-generation Audi Q5 and its close relative, the Porsche Macan, were set up on the assumption that they would be fitted with 18-inch wheels, and were very comfortable when that happened. In each case, fitting 20-inch wheels instead was a disaster.
An obvious contrast was apparent within the Porsche range. By the time the Macan was launched, all 911s came with 20-inch wheels as standard, and their suspension were set up accordingly. It may seem strange that a company could make a sports car with a more comfortable ride than an SUV, but that’s what Porsche did.
Like the 911, the current-generation Renault Scenic and Grand Scenic MPVs have 20-inch wheels too. Also like the 911, they were designed from the start to run on them. The shocks transferred through the low-profile tyres are adequately absorbed by the suspension, and the occupants do not suffer.
There’s little sign that other mainstream manufacturers will follow Renault’s example, but perhaps some day they will. Until then, I’ll always choose the smallest wheels available. My car may not look as good as one whose owner went for the large-wheel option, but it will be far more comfortable to drive.