Wheel Bolts.

[Hutch]

As a follow on to Nigel 27's query about his wheels,
I have Alloy wheels on my Coachman,but the spare wheel is pressed steel. I did query once about when using the spare would the existing bolts be suitable, the hand book states nothing about it other than the different torque settings.
Does anyone know for certain, The wheels must be caravan specific and not Alko.

 

[otherclive]

My Swift had a steel spare and when I contacted Swift I was told the bolts were interchangeable only fitting torques varied and these were detailed in the owners manual. If had four cars, including present with steel spares and interchangeable fasteners.

 

[JTQ]

The spare steel wheel in those cases may be specifically made for doing that, but this is far from universal, and why I warned.

As I had said steel wheel typically adopt spherical seats, whereas alloy more typically adopt conical seats, you just need to check what the bolts and wheels feature in each case.

It however remains the case its very bad engineering practice to use bolts with the wrong register and particularly in the fluctuating and alternating loading case of road wheel retention.

With the wrong registers the bolt contact point will be minimised and because of that such things as finding pot-holes will readily cause some lost of the initial bolt tension, that in turn reducing the clamping force of the wheel to the hub and crucially with that a reduction in the friction, the only thing carrying the face to face shear loads.
Our caravan's and for that most domestic car's static weight and rolling load is carried only by the friction the bolts generate between the wheel and the hub.

Edit: the latter point that our vehicle use friction as the method to carry the load has to be the case to give any remote possibility for "Joe public" to change a wheel roadside without press tools and extractors that would be necessary if force fitted spigoting techniques had bee adopted.