On or around Wed, 28 Jan 2004 20:21:25 +0000 (UTC), "J A Kirby" enlightened us thusly:
a) not all the country has motorways but lorries go almost everywhere and
b) I've seen the effect of average about 2 per day artics on small roads round here - results in considerable damage.
lorry tyres are approx 11" wide, and thanks to large diameter have maybe twice the footprint-length of a car tyre. compare 'em with say a ford fiesta or something, you've got maybe 4x the footprint per tyre.
The 3x3 artic has 22 wheels (if they're all duals except the steer axle, and it's a 6x4 tractor) so it has 22x the area on the road. (assuming the 4 car tyres = 1 lorry tyre, footprint-wise).
However, the lorry weighs up to 44t, whereas the fiesta weighs about a tonne. so the load/area is about double for the lorry. And that was the best possible example: a trailer equipped with super-singles has 14" wide tyres, so the footprint is probably about 5x a car tyre footprint, but it only has 6 of 'em, not 12. Put it behind a 6x2 twin-steer, and the unit has lost 2 tyres as well compared with the 6x4. Now we have 6x5=30 car-tyres on the back, and 8x4=32 on the front for a total of 64 car-tyres, which is only
16x the car's footprint, and it can still be 44t, for 2.75x the load/area. Worse still, on narrow roads, with the super-singles nearly the load is concentrated at the edges of the road, where it's more likely to wear.even at 38t gross, such an artic is still at 2.375 the specific load of the car. And you can run a 5-axle artic at 38T...
of course, there are heavier cars, but then they have bigger wheels - my
110, for example, is on 10" wide tyres, which are nearly as wide as truck tyres, so that's already got about double the area of the ford fiesta.However, all is not lost - yer typical artic running 38t or 44t uses at least 3 times as much fuel as say a TDi disco, and probably at least 5x as much as the ford fiesta above, so it's already paying the extra duty, 'specially as it's about 3 grand for the VED as well.