Date: Tue, 9 May 2000 00:50:50 +0100 From: "Simon Watkins" <siwatkinsnopsamorg> Subject: Re: 9-5 - Abnormal Tyre wear???
Peter Wilkins <wilkinspnopsamnet.au> wrote in message news:gtddhssfhuq6i15m8s99pk639a60uhp1t2nopsamcom... > A couple of "reasons", but more like "educated guesses" really. > > I have a conviction based on some 27 years of driving Saabs that the > "recommended" pressures are biassed a bit more towards a softer ride > than towards better handling and cornering. I defer to your experience :-) I'm on my third 9-5 now, and plan to keep this one till it falls to bits. Great car (apart from the tyre wear!!!). > I found that when I kept to the recommended pressures, the tyres > generally tended to wear on the outside edges more than in the centre, > and the tyres ran hotter than I liked. When I add a few psi, the wear > evens out, the tyres run cooler and the handling improves as well as > the fuel consumption, at the expense of a slightly firmer ride. I wonder if there is a way to determine optimum pressure for tyre wear? Maybe putting permanent marker across the width of the tread and running the car at high speed with different pressures to see which results in the most even wear pattern? > I wouldn't overdo it though, just a couple of psi, and never inflate > more than the recommended pressures for full load. Go any higher and > you won't just get more wear in the centre, you will lose grip when > cornering and be vulnerable to sidewall blowout. Plus having a very > hard ride! Well, there seems to be quite a wide band for recommended pressure - I'm not going out to check at this time of night, but I recall it runs from 32psi right up to 39 or 40 psi. Fair scope for some tweaking and for it to still be within factory recommended limits. > There is also the fact that tyres tend to get neglected and may go a > few weeks (or more) between checks. If they are a little over at > first, then there is a better chance they won't get too low before the > next check. (I know that's a lazy cop-out, but that's me) Well, the last time I checked mine, they were at about 29psi - only 3 under recommended, so I guess that could be the reason for my wear <kicks himself>. I hadn't checked them for some time before that. > I do believe it is better to be slightly overinflated than slightly > underinflated, based on the recommended pressures. However, I would > maintain that a couple of psi over the recommended light load figures > is really closer to correct inflation than overinflation. I'm sure > others would argue with me though, and I'm open to persuasion if > anyone has any hard facts. Your logic makes perfect sense to me :-) I might just try doing something with a permanent marker out of interest though. Simon
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