Tyres!!

[Nbgring]

Ian_UK1 said:

Nbgring said:

Hi Jamie,
maybe I am not quite understanding what you recommend here: do you recommend for use on a Vantage V8 the Michelin PS4 in size 245/40 R19 for the front combined with a PS4S 285/35 R19 for the rear? Is that a real Michelin recommendation that you combine two different tyres? From my experience / belief I would have assumed that such different tyres would cause a dangerous disbalance of the car since - depending on temperature, moisture, surface, but also driving style or trackday condition - the different tyre characteristics would mean that either the front or the rear of the car will have significantly more grip than the other end. Is this a real Michelin recommendation that you can mix these tyres on a high performance car?

This was the reply I received from Mike at Bamford Rose when I asked him the same question re PS4 F / PS4S R. Makes a lot of sense:

".....The water channels are virtually the same, the available grip from cold is more than a driver will push in reality.

Logically, it’s not as if front axle and rear axle handle identically anyway, (different weight balance, driving Vs non driven wheels and rear is going through a LSD), so a slight change in compound between each axle will affect what exactly?

Also, considering the suspension on your car [Sportpack, w/custom geo] the 4S compound will work very well on the rear, will have excellent high speed tendency for a little rear end oversteer, which is exactly what the vantage needs to overcome its front end understeer. The DSC will always catch anything in background, so it’s all risk free / irrelevant worries anyway....."

Ian, that statement - even if made from a highly estimated contributor - may aim towards those users, who really do not belong to the more sporty drivers. First, the water channels of the PS4 and the PS4S are not the same. There is a significant difference between these two tyres. Second, Aston Martin runs a test facility next to the Nürburgring and they do run tons on road tests to get the setup such that front and rear handle almost the same, with a minimal tendency towards understeer. Would they do this if it wouldn´t matter at all? You cite "the 4S compound will work very well on the rear, will have excellent high speed tendency for a little rear end oversteer, which is exactly what the vantage needs to overcome its front end understeer" - but exactly the opposite might happen. The PS4S is the sporty version with more grip. I assume if you equip your Vantage with PS4 front / PS4S rear the car will show strong understeer on dry road conditions and on trackdays, and it may show strong oversteer in rain conditions. I agree that the DSC may catch the worst... But what is if you switch it off on a track day or for a sporty trip? Personally I cannot see why I would mix different tyres on my car.

[anthon]

I have to fit new front tyres to my DB7 Vantage Volante and have researched a lot (except for paying £185 to use the AMOC website!) so PistonHeads to the rescue.
I am lucky to be close to the DB7 specialists Chitern Aston who are constrained to only fitting the AM Bridgestone tyres. The originaly fitted S02 are no longer available so they have to fit the Potenza S001. Now I accept that AM may have tested and specified the S02 originally in 1997 and this may have been the best (for the car at the time) although the cynic in me reckons there is probably a financial tie up between the two companies.
Has AM reviewed the DB& recommendation by doning extensive testing at Nurburgring on the DB7 with the S0? I doubt it. They probably took the closest replacement available from Bridgestone.
Also many reviews show the Michelin Pilot Sport 4 to surpass the Bridgestone S001, quite considerably in some areas, when fitted to many different and similar cars to the DB7. Although I have done a lot of track and road racing I now want a tyre that will be sure footed in the wet and withstand the pot holes and speed bumps on English roads. The Michelin Pilot Sport 4 seems to be the most suitable.
Interestingly Chiltern Aston said I should also replace the rear S02's but they have little wear and are not old. So the S02 and S001 are sufficiently different anyway.
The question then is the PS4 just on the front (with S02 on rear) going to be any worse than a mixture of S001 and S02? Of course eventually I would replace the rears with the same as that on the front.