Tyre speed limits - what's the tolerance?

[Somewhatfoolish]

I just drove from Frankfurt to Nuremburg and annoyingly windscreen said stay at 210km/h. While I did this and interestingly didn't get overtaken once, when I drive back in a few days time I'd much rather do 250km/h (and it's a 340i so perfectly capable of it), cause I feel it's a moral obligation to use a car properly and set a good example to my daughter.

If the speed codes on the tyres, which I didn't check, turn out to acutally be for 250 (and I don't see why they can't be; my winter tyres in the UK generally are) then I'll just do that. If they however are actually set to 210 then what speed can I actually safely do - I assume there's some sort of margin?

[brillomaster]

Unless youve cheaped out on tyres on a powerful rwd car, id have thought they would almost certainly be Y rated, which is good for 300kph.

Or are they on winters or something?

Possible theyre W, in which case thats still good to 270kph.

Anything less than W shouldn't be on the car.

Also why is the windscreen telling you what speed to do? Have you got some speed limiter set or something? But yeah, if tyres are W or Y rated, crack on at 250kph.

Edited by brillomaster on Friday 6th November 03:47

[ST3.14159265358979323846]

These are either H rated winter tyres or the winter tyre limiter has been set.

ETA: The tolerance is whatever the speedo is out compared to actual road speed. If you have an accident and are found to have exceeded the limit of the tyre you don't want to go there.
Check what tyres are on the car and go from there.

Edited by ST3.14159265358979323846 on Friday 6th November 05:59

[SkinnyPete]

A tyre’s speed rating tells you what it’s been tested and certified to handle under specific laboratory conditions. It doesn’t mean it’s guaranteed to sit at that speed indefinitely in the real world.

I know that doesn’t really answer your question, but it’s something to keep in mind.