Moses your running L/T tires like I will be running are the 10 ply or 8 ply just wondering to see how the ride is at 40 psi, The tires I want to run are 10 ply and need a higher psi like you stated. I should of just asked what the psi rating was on a stock aluminum 16" wheel and avoided all the jabber, I liked the Volvo comment

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Its good to see someone has a sense of humour 

I'm using Goodyear Wrangler ATS's, unfortunately they don't give a ply count.

I would say for me 40psi is comparable with the factory tyres,
I could go higher but am using harder springs which ride pretty
rough so I keep it there for comfort. If the car is empty I drop
the rears to about 35, any less and they start to bulge a little.
20-25 on dirt tracks and rock gives good grip and comfort, 12-14 on
beach sand works well.

I cant imagine the alloy rims being a limiting factor, they are generally
stronger than steel rims and my van requires 60psi on those.

Trial and error is the only way to know what works best.