Leaf Sring Bracket/clamp broken on HZJ79

Evening All.

Lately have experienced/seen broken Brackets or clamps on the leaf springs on 3 HZJ79s.

Firstly these utes do cop a shed load of abuse, however the Firm I work for run Bridgestone M880/890 tyres of 7.50R16. Same size as the originals but they have a Ply rating of 14! Sorry don't have a picture of the rubbers. Photo is a Dunlop Road Gripper 8 Ply.

Secondly - these utes have steel trays


I guess working in remote exploration work and the roads been very rough/basic, a softer compound tyre would be more adequate. For traction and durability. Believe me these M890s are heavy and feel 'hard' when driving. I figure that they are not designed for 4x4 work.
Also these tyres are fitted to split rims on a mine site and for 100 Series.

I had just thought that without a tyre giving any 'bounce' or give could cause these brackets/clamps. As with what I have learnt tyres also play a part in a vehicles suspension.

I've mentioned a change in Tyre quality at work but my theory falls on deaf ears!

Could there be any other causes for this breakage?

So far one vehicle has just been fitted with after market suspension.

As mentioned on the sidewall of M880/890s, who would have thought you need a 'SNOW' tyre in the Pilbara!!!!!!!

Image Could Not Be Found

Any thoughts are appreciated