Tyres - XL loading?

[GTRS]

Hi all:

There are a few postings relating to this, but I just wanted to check things over. The guy who's doing all the suspension and brake work on the RS2 has ordered some new PS3s for me 225/45/ZR17 94Y - but not XL. Here is his reasoning - though he is happy to amend to XL

"the XL isnt necessary as its not a super heavy weight car/MPV, the non-XL also is better in terms of tread wear and road noise. I personally don’t see the need for the XL tyre unless you are planning on doing a lot of track use and/or carrying heavy items all the time in the car."

Here are previous postings:

From Auto Express: XL stands for Extra Load – or is sometimes referred to as Reinforced. Essentially, tyres bearing this stamp are designed for heavy cars rather than ones that carry big loads. Not only are they constructed to cope with weight, but also the higher tyre pressure these vehicles need to run at. This marking is usually found on lower-profile tyres used on large cars. It highlights the fact they are built to a higher weight rating, as there is nearly always a standard version in the same size in the maker’s range"


From scillyisles: XL tyres are designed for heavier performance cars. The extra stiffness in the sidewall not only assists with carrying the load but with body roll resistance(handling) and steering response. Both of these aspects are important in a performance car.

Question: is this basically down to a case of trade off between tyre wear (not too fussed) and road noise on the one hand, and steering feel and handling on the other?

How perceptible do others know/think the differences to be?

Many thanks for any pointers

Graham

[scillyisles]

I note that the PS3 is now showing as available in 94Y in 225/45ZR17 on Michelins site. Yippee I have been hassling Costco on this for some time. 94Y is an XL rating so your brake guy is agreeing with me. The other version in Y rating is 91Y which is not.
As soon as Costco have their 20/25% special offer on again I will be ordering 5 of these.

[GTRS]

My mistake - he's ordered 91Y
So, back to my question, I think

(I did see 94Y available on he Michelin site as well, but am struggling to find them anywhere)

[scillyisles]

91Y is not a low rating but what you have got to remember with the RS2 is that a lot of 225/45 tyres are not designed to fit on a 7 " rim. They are designed to fit on 7.5" or wider rim. Given that you are fitting the tyre on a rim that is at/on or below its narrowest recommended rim size, you are stresssing the tyre more than normal. This is most graphically ilustrated by the sidewall bulge you get. The sidwall is where the weight and stress forces are concentrated and I seem to recall that we did have some issues in the past where people using the Michelin Pilot Sport 2 in 225/45ZR17 91Y fitment had sidewall problems. Reading through Michelins blurb on the Pilot Sport 3 and also roadtests of the Pilot Sport 3, it would appear that the Pilot Sport 3 has a softer sidewall than the Pilot Sport 2 hence my recommendation to go with the Pilot Sport 3 in 94Y fitting.
Could I suggest that you speak to Michelin technical as to what they think about fittng the tyre on the OEM 7" rims with the weight and performance potential of the RS2.

[GTRS]

Much appreciated. I'll contact Michelin, and if I get a response will post here

[GTRS]

Here's what Michelin said:


Thank you for your enquiry about tyres for your RS2.

We have little fitment information data for the RS2, we have the tyre size as 205/55 R 16 on a 7J Rim. Our techincal team suggest talking to the Audi Dealership who may be able to advise you.


Hmm. That's not much use

[darkhorse1210]

Goodyear Eagle F1 Asymmetric are fantastic....check out old posts on them....

[scillyisles]

You need to phone them up and ask to speak to the technical dept in person. I have done this many moons ago and they are very good if you explain the issue to them. I did this for Dunlop, Pirelli and Michelin and all their technical department were happy to help.

[Lloyd]

Goodyear Eagle F1 Asymmetric are fantastic....check out old posts on them....

Yes, they are very good for most of the year - but not in the winter. Downright dodgy on ice and very slushy snow.

Also Michelin Pilot Sport 3 are now out and are a newer tyre, but no personal experience. F1's still my current fav with the above caviat.

[darkhorse1210]

"Yes, they are very good for most of the year - but not in the winter. Downright dodgy on ice and very slushy snow."

Agreed, I've had a few 'moments' over the last couple of winters.

But then again how many other summer tyres are any good in the snow?! From the post a few weeks back is soundslike those Nokian (?) winter tyes were excellent...maybe worth snapping a set up in the summer whilst prices are rock bottom

[GTRS]

I called Michelin - as suggested, they were very helpful. The PS3 225/45 R17 91Y is 'designed' for 7.5" width, the range but is rated for range of 7-9.5" at 1230kg/axle. I went over the possible requirement for XL loading, and he said that it's not needed - the rim is wide enough at 7". Reassuringly, he knew what the RS2 was. Out of the two options 91Y vs 94Y XL, he recommended 91Y.

Also, the 94Y is showing as unavailable on all their systems (but that was the last thing I asked them to check).

So, I'm going with 91Y and will report back on them.

[scillyisles]

I called Michelin - as suggested, they were very helpful. The PS3 225/45 R17 91Y is 'designed' for 7.5" width, the range but is rated for range of 7-9.5" at 1230kg/axle. I went over the possible requirement for XL loading, and he said that it's not needed - the rim is wide enough at 7". Reassuringly, he knew what the RS2 was. Out of the two options 91Y vs 94Y XL, he recommended 91Y.

Also, the 94Y is showing as unavailable on all their systems (but that was the last thing I asked them to check).

So, I'm going with 91Y and will report back on them.

[Lloyd]

I called Michelin - as suggested, they were very helpful. The PS3 225/45 R17 91Y is 'designed' for 7.5" width, the range but is rated for range of 7-9.5" at 1230kg/axle. I went over the possible requirement for XL loading, and he said that it's not needed - the rim is wide enough at 7". Reassuringly, he knew what the RS2 was. Out of the two options 91Y vs 94Y XL, he recommended 91Y.

Also, the 94Y is showing as unavailable on all their systems (but that was the last thing I asked them to check).

So, I'm going with 91Y and will report back on them.

My guess is they will be fine for the road but should you do a track day they will wear heavily on the side wall.

[scillyisles]

Went the opposite way to GTRS and opted for the PS3 in 225/45ZR17 94Y rating.
My reasons being :
- the RS2 is quite heavy.
- the 7" rims are right at the edge of acceptable with 225/45 tyres consequently the tyre walls take more stress than normal.

Overall very impressed, ride quality is softer with less road noise and the steering is appreciably lighter with better directional stability. Wet grip seems very good.

[GTRS]

Interesting. I put my thoughts on the tyres in a separate thread on the work I have had done, copied below:

Having had so much replaced - effectively lower half of car overhauled - it's difficult to pin down where the difference is felt, though some things are obvious. Overall, the car feels really taught and much better controlled - all the previous slackness I'd noticed but couldn't quantify has now gone, and the ride is much better (impossible to tell how much the Tyres contribute, if at all). In B road driving, it turns in more progressively (always wondered what that meant; now I know), the steering is a tad more communicative (I can feel the onset of understeer now, instead of trying to work out when it's about to happen), and obviously it's much better controlled over crests and through dips. One of the biggest differences became apparent on the way back - I was consistently underestimating my speed by about 20% and was so busy thinking about all the new parts I'd spent well north of 5 grand on that could have made that difference that it took a little while to realise the obvious - the PS3s: the reduction in road noise is little short of amazing - which also counts as my input to the previous thread on Tyres.