Why 50mph?

[Matt Haigh]

Took my spare off today to check the pressure and grease the bolt.

The spare is a full size steel wheel with an unused Michelin Premacy tyre of the same size/rating as the (Tikehau alloy) road wheels on the vehicle.

I'm wondering why its marked up with 50mph/80kph max speed stickers?

[Multispacer]

Could be for a couple of reasons.

Has the spare got a directional tread on it? [some tread patterns are]

The fact that it's a steel wheel and the others are alloys mean there's going to be a weight difference?

Probably though, it's just the fact it's a generic steel wheel that is used on a lot of PSA models and maybe some do have a spacesaver?

[Pedronicus]

I suspect it is because, if used, there will be unmatched wheels on the vehicle so the 50mph maximum speed is probably enshrined in some law somewhere for the use in emergency only.

[Vlad]

Don't the wheel bolts have different seating profiles depending on steel or alloy? Meaning to use incorrect bolts will be a safety issue?

[RobS]

Because the wheel will be a different width and weight to the alloy on the other side if it is on the front there is a potential for a braking and steering inconstancy. Less so on the rear but the vehicle manufacture could be liable in the event of a incident of lost control if they did not insist on a low limit.

[Pedronicus]

The number of BMWs that I see flying along the M25 well over the limit and one wheel is a spacesaver is beyond belief. Local plod nicked one recently doing 110mph.