Wednesday 16 May 2018

Why I don't check my tyre pressures myself ...

The twin rears on 660/670/700 vans are basically truck wheels and tyres. After 20 years of ownership, I learned the hard way, and I gave up checking my tyre pressures myself years ago . And as for punctures, which are rare, I just limp on 3 rear tyres to safety (front blowouts are different, you should only limp the absolute minimum on the rim - you will ruin the tyre), and then call out breakdown and let them take care of it. I have never successfully managed to undo the rear nuts by hand - they are torqued up with airguns by the fitters and almost impossible to remove with a hand lever/wrench. The other problem is that the supplied bottle Mercedes jack is barely adequate, and is only really usable in absolutely perfect conditions. Most 410D based Hymers are fully loaded at the back - just look at that rear overhang! - and after 25 years the rear springs are tired, making it almost impossible to jack up the rear. So why bother ... that's what breakdown is for. A trolley jack makes short work of it, but who wants to carry one of those?

As for checking the pressures - It is a complete pain in the bum to remove the trims if you have them, and then find an air hose with the right angle nozzle. 90% of all service area air pumps, especially those horrible coin operated ones, are useless - they won't get anywhere near 65psi. And in inexperienced hands you can let out more air than you put in - again I learned the hard way!

Every 3 months or so I just stop by ATS Commercial and ask them to check all my pressures. I always offer to pay, and they never accept. What I have found is that the pressures stay constant for ages and ages, and I have never had a slow puncture. I just drove 5000km over 5 months down Italy and Sardinia, and when I finally called into a garage because I caught a (very rare) puncture in the front, when they checked the rears they were spot on.

I also have the habit of regularly just bending down behind the van, so I can see how the twin tyres sit on the road, every time I fill up, especially on a long journey. You soon get used to the profile, and then you can easily tell if a tyre is going flat.

Of course this is just my personal preference - I am getting on a bit, so anything for an easy life! There is no reason why you can't carry a decent 12v compressor and the correct nozzle, or even a better jack. But new owners should take note - maintaining the pressures and changing tyres on the rear twin wheel Merc Hymers isn't as easy as on a normal family car.

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