Big wheels on a crossover: R19 for summer, R17 for winter?

“Big wheels look great” is more or less how the main argument goes in any car showroom: a crossover on 19- or 20-inch wheels looks more substantial than on “modest” seventeens. The trouble is that the sales assistant quotes only one price for this beauty, the one on the trim-level price list. The remaining bills arrive later, on the potholes and at the tyre fitter’s. So the main point first: a crossover can keep its big wheels for summer, but for winter it is more sensible to fit the smallest diameter the car maker allows.

Where did wheels this big come from?

Crossovers and SUVs now make up more than half of the new cars registered in Europe (54% in 2024, according to market analysts), and as the cars have grown, so have the wheels. In Ukraine, according to tyre sellers, one of the most popular sizes is still 195/65 R15, but 225/45 R17 is already right beside it, and demand for the crossover size 235/60 R18 is rising noticeably.

So why not just fit a bigger wheel with an ordinary tyre, you may ask? Because the space in the wheel arch is limited, and the speedometer, ABS and stability control are calibrated for a particular overall diameter of the wheel and tyre. So the bigger wheel gets a tyre with a lower sidewall, and the height of the wheel stays the same. Here are three sizes that could easily appear in one list: 235/65 R17 has an overall diameter of about 737 mm and a sidewall height of 153 mm; 235/55 R19 gives 741 mm and 129 mm; 255/45 R20 gives 738 mm and only 115 mm. The overall diameter is almost the same, but on R19 there is about 15% less rubber between the rim and the road than on R17, and on R20 a quarter less.

What does a low profile give, and what does it cost?

Let’s be honest: there is a gain. A low, stiff sidewall flexes less in a corner, and the car answers the steering more crisply on a smooth road. That is where the advantages usually end, and the drawbacks begin with the first pothole.

The sidewall works as an extra spring: in a pothole it flexes and absorbs the blow before it reaches the wheel. The lower it is, the less travel it has, and the sharp edge of a pothole can pinch the sidewall between the rim and the road. The cords break, and the air pushes out a bulge in the sidewall (more about aspect ratio). A tyre with a bulge in the sidewall must be replaced, not repaired: at that weakened spot it can burst at any moment.

What the sidewall has not absorbed goes to the wheel and the suspension. A hard hit bends or cracks an alloy wheel, and as a rule it can no longer be repaired (more on this in how cast alloy wheels react to potholes). A mechanic I know has noticed that every spring the biggest crop of bulges, bent wheels and cracked wheels reaches him on the cars with the lowest-profile tyres. Add the harshness with which every joint in the road comes through to the cabin, and the price: a tyre for a big wheel is, as a rule, noticeably more expensive.

A wide low-profile tyre also copes worse with puddles and snow: its contact patch is wider but shorter, and it finds it harder to push water or snow out from under itself (why that is, in the article on tyre width by season).

A smaller wheel for winter: how to do it right?

In summer you can still put up with big wheels, but in winter, when potholes are hidden under the snow, a tall sidewall is needed most (more in when to use alloy wheels). But “smaller” does not mean “any”:

1. Only a size from the car maker’s list. Look for the list on the plate in the driver’s door opening or on the fuel filler flap, but the fullest one is in the owner’s handbook. If R17 is not in it, then it is not intended for your car, and that is the end of it. Ukraine’s traffic regulations (clause 31.4.5 (c)) expressly forbid operating a car if its tyres “do not match the vehicle model in size or permitted load”, so the load index of the winter tyre must be no lower than the standard one.

2. Brake calipers. The powerful brakes of a crossover may not fit inside a smaller wheel even if the bolts match the hub. This is checked by trying the wheel on before the tyres are fitted, not after.

3. Practically the same overall diameter of the wheel and tyre. Otherwise the speedometer, ABS and stability control will lie. The easiest way to work out a change is on the tyre size calculator.

4. Offset, PCD and centre bore exactly as the maker specified for this wheel size. Why there are no “permitted deviations” here is explained in the article on offset, width and wheel diameter; and when buying a second set, check the quality marks on the wheel.

5. Pressure sensors. If the car monitors pressure with sensors in the wheels, the second set needs sensors too, its own or moved over from the summer wheels, otherwise the warning light will stay on all winter (how they work is in the article on tyre pressure sensors).

Incidentally, a winter tyre for a smaller wheel is, as a rule, cheaper, and often narrower too, and a narrower tyre works better in snow and slush.

How to live with big wheels?

If you already have 19 or 20 inches, keep the pressure strictly to the maker’s plate: in an under-inflated tyre a pothole pinches the sidewall more easily. In fact, damage to the cords is often not visible from outside: a tyre can hold pressure and look intact. So after a hard hit, show the wheel to a fitter: they will inspect the tyre from the inside too and check the wheel for runout.

In winter, do not count on four-wheel drive: it does not help you brake, because every car, whatever its drive, has brakes on all four wheels. And the “off-road” tread pattern that suits a crossover so well makes sense only for those who really leave the asphalt: on tarmac a tyre with that pattern is noisier and brakes worse (more in the piece on the “off-road” winter tyre).

To sum up: a big wheel on a crossover is the price of looks, not of safety or off-road ability; for winter the right choice is the smallest diameter on the car maker’s list. Whether you are ready to pay for looks with bulges and bent wheels is up to you. Just remember that a pothole does not ask how much your wheel cost.

All articles on choosing wheels