Any ideas?

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JohnD
Donor 2016
Posts: 2507
Joined: 15 Mar 2001, 00:41
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Any ideas?

Post by JohnD » 18 Apr 2003, 01:43

On a caravanning forum, www.michelin.co.uk/car came under discussion. The tyre selector pages give for the Xantia, 205/60x15 Energy tyres with pressures at 35/32 for standard use and 35/32 for fully loaded. For the C5 they also recommend 205/65x15 Energy tyres with a standard pressure at 34/30 but a loaded pressure of 34/36. Anybody know why there should be such a difference for the two vehicles running on almost the same tyres?

humpy
Posts: 28
Joined: 27 Jul 2002, 19:50

Post by humpy » 18 Apr 2003, 04:30

I'm sure someone with much more knowledge will give you a more setailed answer but i beleive it has to do with front/rear weight distribution. I believe the ideal is 50%/50% but this is not always the case. Perhaps the xantia and c5 have differing ratios.
Of course it is more complex than this. I suppose it is to do with the transfer of weight when the vehicle is under braking or acceleration. Factors which may change this incluge ride height, suspension geometry and wheel base to mention a few.
I'm puzzled by the fact that a whole bunch of models in the same range may be quoted as having the same set of values when a diesel would have a much heavier engine and the weight ratio would be totally different.