Tyre guidance please

[archwayanimal]

I need to replace all four tyres on my 2005 A3 2.0 TFSI Quattro S-Line. Currently has 225 40 ZR 18 all round, front say 92W and rear say 92Y. Frankly have no idea about all of this - do I need ZR rated tyres? What would you recommend? Many thanks.

[alankru]

Z rated tyres are not what you would be asking a tyre supplier for. I'll explain...

(Apologies if you already know this), the values mean:
225 - Width of the tyre in mm
40 - Height of the tyre sidewall, as a percentage of the tyre width. This is your tyre profile (or you can think of it as the depth).
Z - This is a quick reference to the speed rating as it indicates that the tyre is rated at 149+ mph. If a tyre's speed rating is above 149MPH, then it must have this notation, but you need to look at the letter (in your case W or Y) to get the actual speed rating.
R - Indicates that the tyre is Radial (which they all are nowadays)
18 - This is your rim size in inches.

So you would be looking for 225 40 R 18 with a 92 load index and a W or Y speed rating (W speed rating is 168MPH and Y is 186MPH) and because W and Y speed ratings exceed 149MPH, these tyres will also have Z noted in the dimensions.
When shopping around, you are best off getting prices for your tyre in both W and Y ratings (different manufacturers will make tyres for the different ratings, so can get a good price in one or the other speed rating).

In terms of recommendations, I'm afraid that I do not have your tyre size on my A3, but the autoexpress article linked to here references to 225 40 R 17 tyres which are pretty close to what you have.

[archwayanimal]

This is incredibly helpful - thank you for taking the time to explain all of the details. I will look for some 225 40 R18 92Y tyres, non budget!! Cheers, Richard.

[alankru]

This is incredibly helpful - thank you for taking the time to explain all of the details. I will look for some 225 40 R18 92Y tyres, non budget!! Cheers, Richard.

Pleased to help. Sorry, I didn't see in your original post that you require different speed ratings for the front and rear tyres.

As you are intending to replace all 4 tyres, you have the opportunity to try and get the same manufacturer and model of tyre so that the tread pattern is the same all round (to give best performance).

[archwayanimal]

Have just had 4 continental contact sport 5 tyres fitted. Merityre inflated all to 30psi as according to the data on their chart, but inside the filler flap on the car the recommended pressure for 225 40 r18 tyres on this car is 38 front and 35 rear. I assume this must be correct so went with this, rather than what they suggested....?

[alankru]

Have just had 4 continental contact sport 5 tyres fitted. Merityre inflated all to 30psi as according to the data on their chart, but inside the filler flap on the car the recommended pressure for 225 40 r18 tyres on this car is 38 front and 35 rear. I assume this must be correct so went with this, rather than what they suggested....?

I've always found that the data from third party charts is completely different to the manufacturer's recommendations. I would always set it by the manufacturer's recommendations - that way you can never be wrong.

I've just looked at Merityre's website and I see that they offer computerised 4 wheel alignment using Hunter equipment (see Wheel alignment available at all our Merityre branches). Now that you have 4 new tyres, it is recommended that you have your wheels aligned, to prolong the life of your tyres, and you will also find that the car will drive a lot better. I've had my wheels aligned a number of times and I would personally 100% recommend it. Take a look at this website:
http://www.alignmycar.co.uk as it explains what is carried out and you can also look at other centres, that also have the Hunter alignment equipment, so that you can phone around for a good price. Some centres charge per axle, per adjustment required (which could potentially be 3 or 4 adjustments) or a flat fee. The tracking should take 1-2 hours to do correctly - be wary of fast fit tyre centres that do it quicker than this as they are likely to only make some adjustments and not bother with the full range of adjustments that can be made (so always ask how long it takes to do).

Sorry, I should have told you about this earlier, but it has only just come to me as I have had mine done today (my steering wheel was not driving straight).

[archwayanimal]

Many thanks!