FOR OWNERS OF MERC 6 AND 7 SERIES VANS - REAR TYRE BLOWOUTS. (Double back wheels - not 5 series vans)
There have been a few posts recently about this, so I thought I would do a quick blog about it. If you have never had a rear puncture or blowout, then file this info away for future reference.
Changing a back tyre on these vans at the road side is not for the fainthearted. Our vans are usually well loaded and heavy at the back which makes them tough to jack, and the wheel nuts have been powered on by the original tyre fitter with a power tool, and are very difficult to undo with a normal wheel brace. By the time you have got out the spare, changed the wheel (if you can even get it off), and remounted the blown wheel into the spare carrier, you will be a filthy sweaty, cursing mess. And you will still have to visit the tyre place anyway to fix the spare and have the nuts re-torqued. So why bother!
By far the best solution is to call out breakdown, put the kettle on, and let them do it. They will have a proper trolley jack, and a wheel brace with a long extension arm. That's why you pay for breakdown cover.
Can you drive the van on 3 back tyres? Yes you can. Slowly, to the nearest point of safety. If the bad tyre is shredded and banging like crazy, it usually sounds worse than it actually is, so take it very slowly and just get off the carriageway. If the tyre isn't too shredded, then you can drive several miles if you have to. Keep the speed down to around 20mph. If you are lucky you will be in range of the nearest town with a tyre depot, and just park outside till morning - blowouts always happen in closing hours - Murphy's second law.
Rear blowouts on these vans can cause damage to the underside of the van, so make sure the area is thoroughly inspected afterwards.
If you are the self sufficient type and have big muscles, then one day you should practice jacking up the rear of the van, and loosening a wheel nut, so you know just what is involved. The Merc supplied bottle jack and wheel brace are barely adequate - fine for a lightly loaded panel van maybe, but not a fully loaded rear heavy 4 ton motorhome. Having done this, then you should "tool up" as necessary - then you will be prepared to do it yourself in the future.
If you are a relatively new owner with little experience of double back wheels, you should also get in the habit of visually inspecting the back tyres every time you fill up with diesel in the daylight, on the forecourt. As you look under the van from the back, you can compare the way they bulge as they sit on the road. They should all look roughly the same, and a tyre losing pressure will be obvious. If you have a slow puncture or other problem, you will soon see the difference, and can then have them checked - you can't check the pressures on these commercial tyres at slot machine operated air pumps - you need to call into ATS or similar. I have found over many years that in good condition tyres keep their pressures for months and months without problem. But if you catch a nail in the road, and develop a slow, then the other tyre will keep on taking the strain for days or weeks, until the fateful day. A quick visual check every time you fill up can save a lot of hassle. Another trick is to just rest your hand on each tyre and feel the temperature. A tyre on the way out will be noticeably hotter than the others.
But for the rest of us mere mortals - it's best just to call out the breakdown boys.
A rear blowout is also usually the time to inspect the whole set, and rotate and replace as necessary. The tyre next to the one that blew should also be carefully inspected, as he was the hero that saved you, but may be injured himself!
These comments also apply to all vans with 4 wheels instead of 6, except that you should only attempt to move a 4 wheeled van as a matter of safety, as driving any distance on the rim will finish off a tyre that might have only needed a puncture repair, and may even ruin the wheel.
Front wheel blowouts are mercifully rare, but usually easier to change, but it's best to practice this also in advance, just to check that your tools and skills are up to scratch.
