Speed rating of tyres on A4 Avant TDIe

[sprint]

No, the speed rating of the tyre has to be in line with the max speed of the car. A 136 TDie has a vmax of 130 mph so the tyre speed rating has to exceed this. In this case you could use a V-rated tyre as at 150 mph this also exceeds thevamx of the vehicle.

In a lot of cases the tyre manufacturers limit the number of speed ratings thay make for a given tyre type and size, so usually go with ratings that are towards the top end of those vheicles they will be used on.

As others have pointed out, the load index is a much more critical number to match correctly.

Thanks for the reply and clarification.

I have always been led to believe, certainly by most tyre dealers, that you have to maintain the original manufactures fitted speed rating.

So why on earth do manufactures fit tyres that are some two or more speed ratings above the actual max speed of the car?

Are the characteristics of the lower rated tyres, grip, noise, wear etc significantly worse than those of the higher rated tyres to justify the extra cost they very often demand?

[zollaf]

the speed rating is basically the max speed the tyre can go at for prolonged periods before it falls apart. it is strange that a tyre maker will produce a tyre to travel at 168 mph though.
incidentally, there is no legal requirement to have tyres of any speed rating on any car, so you could stick h's on a veyron. if the driver exceeds the limit of the tyre, thats where the problem starts. but why we need anything over 70 in this country is just laughable. of course, a y rated tyre is a lot more money than an h.

[YawnGumbo]

Thanks for all the replies. I took the car back to Kwik Fit on Sunday and got the tyres balanced again. Journey home and they seemed a bit better. I'm driving down south this weekend in it so we'll see if it makes any difference and if the mpg is any better. Fingers crossed!