In short. A second set of wheels for winter is worth having if you change tyres twice a year: the tyres stay on their own wheels, so each change is a wheel swap rather than four tyres taken off, refitted and balanced. Going one size down is often possible, but the car maker's list decides, and the brakes set the floor: on a Polestar 2 with the Performance brakes, for example, the manual allows only 20-inch Performance wheels. Steel stands up better to salt and abrasion and costs less; alloy needs washing and a sound finish. If your car reads a sensor in each wheel, the winter set needs four sensors of its own, and the American standard (FMVSS 138) tells owners to check the warning lamp after changing wheels. No law in the United Kingdom requires winter tyres; Quebec does, from 1 December to 15 March.
Do you need a separate set of wheels?
No rule anywhere we looked requires winter wheels. Some places require winter tyres, and a second set of wheels is simply the easiest way to carry them.
| Country or province | What the rules ask in winter | Pressure monitoring |
|---|---|---|
| United Kingdom | No requirement to fit winter tyres at any time of year, according to Michelin UK. The Highway Code (rule 230) warns that stopping distances "can be ten times greater than on dry roads" in ice and snow | The MOT checks the warning system on passenger cars first used on or after 1 January 2012 |
| United States | Not covered by the federal standard we read; FMVSS 138 deals only with the warning system | Required on passenger cars, multipurpose vehicles, trucks and buses up to 10,000 lb GVWR built on or after 1 September 2007, except vehicles with dual wheels on an axle |
| Quebec | Every tyre must carry the mountain and snowflake pictogram, or be studded, from 1 December to 15 March, on vehicles registered in Quebec | See the Canada section below |
| Ontario | The province's page advises four winter tyres, without stating a requirement, and says insurers may give a discount | As above |
| Australia | No winter tyre rule found. In New South Wales, two-wheel-drive vehicles entering Kosciuszko National Park between the June and October long weekends must carry snow chains | We found no Australian Design Rule requiring it on cars |
The details for Quebec and British Columbia, studs included, are in our guide to winter tyre laws in Quebec and BC; for the UK, when to fit and remove them is in winter tyres in the UK.
What a second set saves, counted. This is our own arithmetic over five winters, for one car, assuming the winter tyres last the five winters and are changed every spring and autumn.
| Over five winters | One set of wheels, tyres changed each season | A second set of wheels |
|---|---|---|
| Seasonal changes | 10 | 10 |
| Tyres taken off their wheels | 40 | 0 |
| Tyres fitted to a wheel | 40 | 4 (once, at the start) |
| Balancing operations | 40 | 4 |
| What you store | Four bare tyres | Four complete wheels |
| Extra sensors (direct system) | None | Four |
If the winter tyres wear out before the fifth winter, add one more fitting and balancing of four. The money side depends on your fitter's prices, which we do not quote. Swapping complete wheels at home is possible if you have the car maker's jack points and a torque wrench; if you work under the car, it must be raised and resting on axle stands, never on the jack alone.
How far can you size down?
Start with the car maker's list. Car makers often list several wheel and tyre sizes for one car. Michelin gives, as an example, the five sizes listed for one 2021 compact hatchback, from 15 to 18 inches, and says that the sizes provided by the car maker are the ones to respect; outside them, "in some countries" an exemption is possible if the tyre's diameter stays within -2 per cent and +1.5 per cent. We calculated what each listed size means:
| Size (from Michelin's example) | Sidewall height | Overall diameter | Against 205/55 R16 | Load index and load per tyre |
|---|---|---|---|---|
| 195/65 R15 | 126.8 mm | 634.5 mm | +0.41 % | 91, 615 kg |
| 205/55 R16 | 112.8 mm | 631.9 mm | reference | 91, 615 kg |
| 205/50 R17 | 102.5 mm | 636.8 mm | +0.78 % | 93, 650 kg |
| 225/45 R17 | 101.2 mm | 634.3 mm | +0.38 % | 91, 615 kg |
| 225/40 R18 | 90.0 mm | 637.2 mm | +0.84 % | 92, 630 kg |
Sidewall height is width × aspect ratio; overall diameter is the rim diameter (25.4 mm per inch) plus two sidewalls. Loads are from Michelin's load index table. Three things follow. The car maker keeps the overall diameter almost constant, within one per cent here, so the speedometer and the driving aids see the same wheel. The smaller wheel carries a taller sidewall: going from 18 to 15 inches adds 37 mm, about 41 per cent. And every listed size keeps a load index of 91 or more, 615 kg per tyre at least. You can check any pair of sizes with our tyre size calculator.
Why narrower helps in snow. In 2018 the German motoring club ADAC fitted five widths of the same winter tyre, from 195/65 R15 to 225/40 R18, to a VW Golf: the same two extremes as the table above. The narrow tyre did better in slush, on snow and against aquaplaning; in water 7 mm deep, the 225 tyres lost contact at about 70 km/h and the 195 tyres only at well over 80 km/h. The wide tyre did better on dry roads, and all five sizes were rated "good": the ADAC found the gap between widths smaller than the gap between tyre models of one size. It added that chains can usually be fitted only to the narrower sizes, and that the wheels a car was delivered on are not always compatible with chains. Transport Canada makes the same point more bluntly: wide, high-performance tyres not designed as winter tyres "aren't suitable for snow-covered roads".
The brakes set the floor. A smaller wheel has to clear the brake calliper. The Polestar 2 handbook shows how firm that limit can be: 19- and 20-inch standard wheels are not suitable for cars with the Performance Pack, and only 20-inch Performance wheels fit the large Performance brakes, so on that version there is no smaller winter wheel in the maker's list. The same car can therefore allow a smaller winter wheel in one version and none in another. How clearance is measured, and why the spoke shape matters as much as the diameter, is in our guide to brake calliper clearance.
Speed rating. Michelin says a lower speed rating than the original is acceptable only for tyres with winter capability, winter or all-season, and Michelin UK adds that in that case a reminder of the lower maximum speed must be displayed where the driver can easily see it. Load index is another matter: Michelin says a higher load index than the maker's is fine, gives no such exception for a lower one, and warns that sizes outside the maker's list can mean tyres with insufficient load capacity. In Great Britain, the MOT checks load and speed ratings on classes 5 and 7 only, not on ordinary cars, so on a car the check is yours.
Onyx Forged does not recommend a size or an offset. The list in your handbook, on the door-pillar label or in your registration document, read for your exact version and brakes, is the reference.
Steel or alloy against road salt
| Point | Steel | Alloy (cast or forged) | Source |
|---|---|---|---|
| Salt | Closed shape protects better against road salt and abrasion | Anti-freeze agents are harmful to aluminium alloy; corrosion leaves a white powder and, if it reaches inside the wheel, can reduce its strength | auto motor und sport; JAWA |
| Care | Little | Rinse with water after salted roads, use a neutral cleaner, as an acid one can discolour the surface | JAWA |
| Cost | Cheaper to buy and to replace | Dearer | auto motor und sport |
| Pressure sensors | Check that the sensors fit the rim | Same | Transport Canada |
The Japan Light Alloy Wheel Association (JAWA) advises rinsing the wheels after driving on roads treated with anti-freeze agents, or after parking for a long time by the sea, and cleaning and drying them fully before storage. The German magazine auto motor und sport credits alloy with lower weight, but it is not automatic: in one car maker's catalogue, a steel wheel was lighter than two alloy wheels of the same size, as our guide to alloy and steel wheels shows with figures. In our reading, a forged or cast alloy set can serve through a winter if its finish is in good condition and it is washed regularly.
Pressure sensors in the winter set
There are two kinds of system, as Transport Canada explains: one uses the ABS sensors and compares the speed of the wheels, since an under-inflated tyre turns slightly faster; the other has a pressure sensor in each wheel. With the first, the winter wheels need nothing, but the system must be reset after the change: Transport Canada says a malfunction warning comes on "if the tires are changed or the tires are rotated and the system is not reset". With the second, the winter wheels need their own sensors, of the right type for the car: Transport Canada warns that with winter tyres the system may not work properly otherwise, and that new rims must accept the sensors.
United States. FMVSS 138 applies to passenger cars, multipurpose vehicles, trucks and buses with a gross vehicle weight rating of 10,000 lb (4,536 kg) or less, and since 1 September 2007 to all of them. The lamp must come on within 20 minutes once a tyre is 25 per cent below the maker's recommended cold pressure (or at a minimum set by the standard, whichever is higher), and a malfunction warning must also light within 20 minutes of a fault. The standard makes the owner's manual explain that fitting "replacement or alternate tires or wheels" can stop the system working, and it requires the sentence "Always check the TPMS malfunction telltale after replacing one or more tires or wheels."
United Kingdom. The MOT checks the warning lamp on passenger cars first used on or after 1 January 2012; a system malfunctioning or obviously not working is a major defect, which means a fail. Our guide to the MOT, TPMS and aftermarket wheels explains how the tester reads the lamp.
Canada. We read the Motor Vehicle Safety Regulations, current to 21 September 2026: the list of Canadian standards in Schedule III goes from standard 136 to standard 141, with no standard 138, and the words "tire pressure" do not appear in the text. Transport Canada files pressure monitors under driver assistance technologies. We could not find a Canadian rule that requires them, which does not mean your car has none: many cars sold in Canada carry one, and the advice above applies to them.
Australia. We found no Australian Design Rule requiring a pressure monitoring system on cars. If your car has one, its handbook says how to reset it.
Whatever the country, sensors are fitted, and programmed where the car needs it, by a tyre fitter; the handbook gives the reset procedure. The valve that carries each sensor is covered in our guide to tyre valve stems and TPMS valves.
Fitting and storing the set
- Mark the wheels. The Polestar handbook asks you to note which side each wheel came from, L or R. Note front and rear too.
- Check the tread. Polestar advises against driving on winter tyres below 4 mm, Transport Canada says not to use tyres worn close to 4 mm on snow, and Quebec recommends at least 4.8 mm in winter.
- Fit four. Transport Canada says winter tyres go on all four wheels, of the same type, size, speed rating and load index; Ontario says to install four and never mix types.
- Tighten to the car maker's torque, in a cross pattern, and set the pressures to the maker's figures. Transport Canada notes that a tyre set in a warm garage will be under-inflated when it is below zero outside, so check them cold.
- Run studded tyres in gently. Polestar says 500 to 1,000 km (300 to 600 miles).
- Store the other set. The ADAC advises a cool, dark and dry place, 0.5 bar above the maker's pressure before storage, and complete wheels lying flat or hanging; bare tyres stand upright and are turned every few months. It also says a tyre is finished after eight to ten years, whatever its tread. More in how to store tyres and wheels between seasons.
If a wheel has hit a kerb or a pothole hard during the winter, or the car pulls or vibrates after the change, have it checked before you drive again.
Winter wheels from Onyx Forged
Onyx Forged is a French brand of made-to-order forged wheels, designed to JWL/VIA standards. We do not choose your winter size: you give us the size from your car maker's list, the Onyx Forged design office works out the set for the car as you described it, and the email we send after payment shows you the dimensions before machining. Tell us in your reply whether you will move your sensors or fit four new ones. The tyres, sensors, programming and fitting are done by your tyre fitter.
Frequently asked questions
Should I get winter wheels or just winter tyres?
If you change tyres twice a year, a second set of wheels saves taking four tyres off their wheels, refitting and balancing them at every change: 40 times each over five winters in our count, against four. If you keep winter tyres on all year or never fit them, it saves nothing.
Can I put smaller wheels on for winter?
Often, within the sizes the car maker lists for your exact version. The brakes set the floor: the Polestar 2 with Performance brakes, for example, allows only 20-inch wheels. The listed sizes keep the overall diameter within about one per cent and the load index at the maker's level.
Are narrower winter tyres better?
On snow, in slush and against aquaplaning, yes in the ADAC's test of five widths; on dry roads the wide tyre did better. The gap between widths was smaller than the gap between different tyre models of one size.
Steel or alloy for winter wheels?
Steel is cheaper and, according to auto motor und sport, its closed shape stands up better to salt and abrasion. Alloy needs a sound finish, rinsing after salted roads and a neutral cleaner. Both work if they fit over the brakes.
Do winter wheels need TPMS sensors?
If your car has a sensor in each wheel, yes, four of the right type, or the system may not work and a fault lamp can fail the MOT on a car first used from 2012. If it uses the ABS sensors, no sensors are needed, but the system must be reset after the change.
Is a lower speed rating allowed on winter tyres?
Michelin says yes for winter tyres only, and in Europe a reminder of the lower maximum speed must be visible to the driver. Michelin's exception covers the speed rating only, not the load index.
Are winter tyres compulsory in the UK, the US, Canada or Australia?
Not in the UK, according to Michelin UK. In Quebec, yes, from 1 December to 15 March. Ontario advises them without requiring them. In New South Wales, two-wheel-drive vehicles must carry chains in Kosciuszko National Park in the snow season. The American standard we read covers the pressure warning system, not winter tyres.
How should I store the other set?
Cool, dark and dry, 0.5 bar above the maker's pressure, complete wheels flat or hanging, according to the ADAC. Mark each wheel's position first.
Where to go next
If you are planning a second set, design a set of wheels from the size in your handbook.
Sources
- Regulations and official pages: FMVSS No. 138, 49 CFR 571.138; Canada, Motor Vehicle Safety Regulations, C.R.C., c. 1038; Transport Canada on tire pressure monitors, using winter tires and amending the Winter Tire Regulations; Quebec, requirements for winter tires; Ontario, winter driving; The Highway Code, rules 228 to 231; MOT inspection manual, section 5.2.3; NSW Government, driving in snow.
- Tyre and car makers: Michelin on changing tyre size, load and speed ratings and European winter tyre laws; Polestar 2 handbook, wheel and tyre sizes and winter tyres.
- Tests and care: ADAC, winter tyre widths compared and storing tyres (in German); NAPAC, JAWA division, wheel care (in Japanese); auto motor und sport, wheel materials (in German).
All pages were read on 16 October 2026. The ETRTO Standards Manual, which sets tyre and rim dimensions, is not freely available and was not read.
The Onyx Forged design office.