Tread carefully when fitting tyres
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I’ve talked about motorhome tyres quite often in the past, but I’m returning to this important topic because I’ve recently become aware of a different issue, mostly involving VW vehicles, but actually applying to any converted panel van.
The issue is fitting the right tyres. I don’t mean camper-specific tyres; in my opinion, the problem is car tyres on large-diameter rims. I’ve seen this myself on a couple of T5 and T6 conversions, where the converter has fitted 17- or even 18-inch wheels and super-low-profile tyres, as they “look good”.
The trouble is, not many commercial vehicle tyres will be made in these sizes, especially with ultra-low profiles, and many car tyres simply do not have sufficient load rating for a ’van.
Looking at load ratings
Your typical 3.5-tonne ’van will have axle load ratings of around 1800kg for the front and 2000kg at the rear. These are the maximum weights those axles can safely support.
So the tyres on a 2000kg rear axle need to have a load rating of at least 108, which gives 1000kg per tyre. You would typically use a higher load rating to give a safe margin.
Many 18-inch tyres only go up to a 91 rating, which is just 600kg per tyre, and when you then consider that most campervans are close to, if not over, their weight limits, you can see that this is a recipe for disaster.
I read of one such set-up recently, where a Sprinter van conversion failed its MOT because its tyres had insufficient load rating for the vehicle. This was despite it having passed the test for the previous five years with those same tyres in place. Nothing had changed legally, it was just that the tester in this instance had spotted the problem and issued a failure notice.
Risking blowout or collapse
T5s and T6s can sometimes get away with this, if they’re the smaller weight variants, but when you come to a long-wheelbase Sprinter, which could have an MTPLM of four tonnes or more, fitting car tyres can be a really bad idea.
In my opinion, larger-diameter rims can also be suspect – if they were intended for a big SUV-type car, they won’t have a high enough load rating, either. A heavy vehicle with insufficient load rating on tyres and wheels could at the very least suffer a blowout, but worse would be for a wheel to collapse – imagine that at 60mph on a busy motorway!
The final irony is that ultra-low-profile tyres will almost certainly ruin the ride quality, too, and all in the name of appearance.
‘The issue is fitting the right tyres. I don’t mean camper-specific tyres; the problem is car tyres on large-diameter rims’