mick.harris":2lrbxd7g said:
Dulan or anybody really !!!
I was going to PM you, but it may interest others on the forum,
I've read most of your threads with interest on the forum and you certainly know your stuff,and you also have a mega low mileage VEE,
I've just took my car to get a screw removed from a rear tyre at the local tyre shop,
after a bit of car chat the owner pointed out that my car was on original tyres ,(done 7000 careful miles) and although in A1 condition should be changed regardless of condition after 5 years,
he mentioned his supplier swap his stock after they have been on his shelf after 5 years (michelin recommend 6 years),
something to do with the DOT code on the tyre,
new one to me , has anyone else heard of this ?
Mick, everyone will have their opinion/view re tyres based on their experiences, so here is mine, which is based on my own experience, research, conversations with people in the know, and last but not least the vehicle manufacturer's recommendations.
My experience is mostly based on Porsches, since I have owned them the longest - 12 years and counting......
Tyres can become hard with time, which is evident by a certain "shine" developing on the surface/sidewalls. When this happens tyre performance in the wet will be an issue (reduced grip and auqaplaning). It will also cause the car to understeer when you go into a corner fast (i.e. less grip offered due to the hard surface so the front end will wash out wide).
Hard tyres may also lose pressure when left stationary for periods of time, and may also begin to crack, especially on their sidewalls.
If there are any signs of cracking on the side walls I would replace those tyres immediately, but only in pairs, and on the same axle, and never mix brands, or even different models from the same manufacture, due to the differing levels of grip and composition that may (adversely) affect the car’s handling.
Below is an explanation.....
Brand and Model of Tyre:
How a car behaves with each brand and model of tyre may differ from one to another, which is why certain manufacturers make tyre testing and integral part of their model development, and approve certain brands and models of tyre. Porsche certainly do that - all tyres approved by Porsche are "N" rated (i.e. they have N0, N1, N2, N3 etc) stamped on the side walls.
This article gives a good explanation:
LINK
Age of Tyre:
As with everything tyres too tend to degrade with time (i.e. the level of performance drops off with time). This is especially true with R5 Turbos since their custom Michelin TRX tyres were harder than normal to begin with and with time they get harder still. Apparently lethal in the wet, which is why most owners changed both rims and tyres (the tyres were specifically manufactured to suit the non-standard rims). This information came from John Price (Tarmac Rally Champ.), who rallied 5 Turbos and 6R4's. Spent half a day chatting about R5 Turbos when John checked out an R5 Turbo for me.
How to check the age of a tyre:
LINK
Having said that, all of the above needs to be put into context and applied to how you (intend to) use your car. If you (only) use the car for spirited drives and/or track days then I believe tyres are very important. After all the realtively small four contact patches are the only ones between you and the road.
For me personally it depends on the car. For example, the 796-mile LY Vee never gets driven as it is dry stored, and still has its original Michelin PilotSport 2's in an as new condition (well the whole car is in an as new condition). As such, its tyres will only get changed when absolutely required. Mechanically it is top notch having just had a full engine-out service by Scott.
When I viewed the Blue Vee (#002) in August 2011 it had Falken 452's on the front and Michelin's on the rears with 5mm tread. To me that was a big no-no, so the deal was to have the rears changed to Falken 452's, which I had not experienced before but was willing to give it a try since many Vee owners were using them with positive results. Having owned the Vee for over a year now I cannot fault the Falken 452's for the use I put them through - spirited road use in the dry, and zero track use.
The 968 Club Sport is being used as a "daily driver" in all weathers and on track (not very often now). It runs Toyo Proxes T1-R's and I find them very good. Over the 8 years I have it tyres were changed twice – first with the T1-S then on to the T1-R’s. Now you may say that the Toyo’s are not N-rated, and you are right they aren’t. However, I sought feedback from fellow 968 owners and decided to use them based on that feedback. So even though this is a deviation from the norm it was a concious, pragmatic decision since the Toyo’s price/performance/durability ratios are spot on for a car that needs to be an all rounder. Highly recommended.
All of the above tyres are well within 7-years of manufacture so there is no issue.
The fronts (Pirelli P-Zero Assymetrico) on the 993 RS are now coming up to 8 years, and they have gone off - losing pressure when stationary and there is a bit of a "shine" on the side walls. No cracks though. As such, all 4 tyres will be replaced with N-rated ones next summer, if I decide not to dry store it. They still have around 5mm tread left all around.
The Alfa SZ I have just purchased is another story. The SZ has an incredible amount of grip (supposedly it can pull 1-1.4g in corners), and runs (minus) -2 degree camber in the front, so the front inner edges are prone to wear. As such, the fronts are getting replaced with Bridgestone S-02A's (the rears have S-02's with 5mm tread left). I haven't had the car long enough for me to form a firm opinion as yet but I am being safe and making these changes now rather than having to learn the hard way. Once all 4 Bridgestone’s are worn I will probably switch to Toyo Proxes.
As such, the above is a summary on how I approach the subject of tyres. Hope it helps.I would certainly like to hear other people's experiences. One will never have enough knowledge since one never stops learning new things.
Lastly, here is an interesting clip:
LINK
Dulan
