Tyre load index class 7

Column 1 = Load Index

Column 2 gives the max load capacity for single wheel application ie steered axle.

This would also apply for class 7 with single wheels on the rear axle.

Column 3 gives the max capacity when the wheels are fitted in pairs, old style Transits, Sprinters etc with 4 wheels on the rear axle instead of the more modern trend for single wheels.

For old style twin wheel axles there is a trade off in that the total weight capacity is less in twin configuration that in single.

This also applies across HGV & PSV's, it's a safety buffer due to a number of variables. Twin wheels setups tend to run at a higher temperature so there's a reduction in weight capacity as an operating margin.

You're welcome. My brain still works, feel free to ask.

Going back a while, I sent the following to the DVSA. I received no reply (as I'd come to expect when you have a valid query). However, shortly after, the Minor Defect, 'A tyre obviously under inflated' appeared. Any 'Major' or 'Dangerous' was going to increase the national failure-figures so was never likely to hit the headlines but, I think you will agree, could not be ignored......




As the MoT inspection manual is currently being reviewed, it seems an appropriate time to request this case (below) for inclusion.

Where a Class VII twin rear wheel vehicle is submitted for it’s MoT test in an un-laden, or indeed partially-laden condition, with one rear tyre deflated, this defect is not usually immediately obvious as the other (inflated) tyre on the same side supports the vehicle weight.

Therefore the load rating / bearing capabilities of the deflated tyre (a testable item) will, in effect be zero. In this case then, the vehicle ought to fail it’s test on safety grounds in that it will fall well outside of the load index/axle ratings. But, as a ‘flat’ tyre (as in this case) is not a reason for rejection and as there is no prescribed method of inspection for checking tyre inflation, the vehicle will subsequently be allowed to take-on it’s load (or more load), bringing it anywhere up to it’s DGW of 3500kg and immediately become, arguably, dangerous bearing a valid MoT certificate.
The handling characteristics will under particular driving conditions, certainly become detrimentally affected. A similarly configured Class 5 vehicle will be the same with the exception of it’s cargo; Just think about that for a minute!

With the rear suspension jacked in the prescribed way, a heel bar ‘lifting’ each rear tyre in turn from underneath will immediately reveal (by the indent) a significantly under inflated tyre, and will realistically add little or no extra time to the test.

I am therefore proposing that in the name of safety you change the MoT test accordingly adding a reason for rejection along the lines of .........
‘Axle 2, significantly under inflated tyre’. (Identified by it’s position)

Or if this is not possible or you disagree in any way, please explain in fullest detail why.

Thank you

David Meredith MIMI
MERE0002

Thank you the outer sill has now got me thinking I have watched some YouTube videos as recommended and looks like the outer part of the sill is for cosmetic reasons and not structural

Just a thought regarding class 7 dual tyre arrangements. (I don't test them) If an inner tyre were deflated such that the weight was transferred to the other tyre, which would overload it, then would that tyre walls not deform such that they would bow outwards and cause "Rubbing Contact" between each inner tyre wall?

If that were so, is there not a rfr for tyre wall contact on class 7 vehicles!

Just my tuppence worth.

I suppose things can only get better (or worse as the evidence) seems to show these days!!