Possibly a silly question RE truck wheels.

[sebhaque]

Apologies if it's a stupid question.

Was walking past a truck parked up at work earlier and I started wondering - why do trucks have different front wheels and rear wheels (both on rigid and artics)? I always thought that unsprung weight on the driven wheels should be relatively low compared to non-driven wheel - and you see trailers on both single-axles and duallys. Most trucks have front wheels that "poke" outwards and recessed rear wheels.

What's the reasoning behind it? I would assume the dually trailers are due to the weight of the loads the trailer's expected to carry - but I'm sure I've seen big rigid trucks with the same wheels front and back. Is the main reason for the difference in wheel due to the load the vehicle's designed to carry?

Appreciate it's not the most interesting of subjects for a Monday night but I'm curious.

TIA

[LouD86]

They are normally the same wheels, just fitted in different ways. Imagine at the rear, your normally double wheeled. The wheels are fitted are per the front, to clear the brakes, then the other wheel butts up against the face, so you get to see the "rear" as such of that wheel.

Hope that helps?

[sebhaque]

Thanks for the explanation. So if you were to take the wheels off the front axle of a lorry and swap them over, you'd be looking at something akin to the rear wheel setup?

Also, hello new forum!

[Super Slo Mo]

Yes. Generally they're identical. We always used to have identical tyre sizes too, as it makes things a lot simpler when it comes to tyre/wheel changes etc.

Some years ago there was a bit of a fashion for fitting large front tyres, this saved on tyre wear and thus money as tyres are expensive. However, it also lead to higher fuel costs, and there came a point where the savings were wiped out by the fuel costs.

In the case of the company I worked for, we used to put brand new tyres on the front and re-cuts on the drive axles (once the tyres fitted from new had worn, of course).

[s p a c e m a n]

Yep, they're the same wheels but they're just mounted face to face on a twin wheel axle so you're seeing the back side of the wheel. Vans do it too, have a look at the rear wheels on tipper/recovery transits and you'll be seeing the back of the wheel.

[GC8]

sebhaque said:

Thanks for the explanation. So if you were to take the wheels off the front axle of a lorry and swap them over, you'd be looking at something akin to the rear wheel setup?

Also, hello new forum!

Yes, sort of. You cant actually do it though, because steer tyres are different to driven tyres.

[Super Slo Mo]

GC8 said:

Yes, sort of. You cant actually do it though, because steer tyres are different to driven tyres.

They don't have to be do they? I'm sure we used to put re-cuts on the drive axles, but might have got mixed up. Perhaps our re-cut steering tyres went onto our 4 wheeled urban trailers with duals.

[GC8]

Steers on a driven axle might be alright, but drives on a steer is very bad.

[Super Slo Mo]

Yes, I imagine they would be!