Any tyre boffins out there (1 Viewer)

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I have just replaced my rear tyres with 8ply not 6ply like the ones they were replacing. Not a problem I thought. Stronger proper commercial tyres that were recommended by the local tyre outlet so I went for them.
I’ve had them for a couple of weeks now with a few different pressures 54-50 and now 48psi. My problem is that I appear to be getting a rougher ride. I can hear things that I didn’t hear before like cutlery and saucepans and it starting to irritate me a lot.
Is this my imagination or are 8ply tyres best restricted to commercial users where ride quality is less important. it's that bad I'm thinking of changing them again.
Edit.. One other small point I had to brake hard for a pheasant yesterday, it was damp and possibly a bit slippery but the rear wheels locked, not a problem but in three years that was the first time. Possibly a coincidence.

 

[gazz]

8 ply will be stiffer, especialy the side walls, which is handy for commercials, but not for light weight motorhomes.

my van i have to use 8 ply tyres because it's a 4.5 tonner, i get a bit of a rough ride, but i'm used to it, i just made up holders for plates and glasses to stop them ratteling.

 

[Snowbird]

I think more depends on the tread patern than the ply rating.
I know the diference that road tyres make on my 4x4 as opposed to off road or M&S tyres.
If the new tyres are of the knobly tread patern,mabe thats the problem.

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[lebesset]

for a start the tyres won't have either 6 plies or 8 plies ; they may have the old fashioned ply RATING marking , which was the number of cotton plies that their strength it is equivilent to

the current system is of course load index , which tells you the maximum load the tyre can carry in single or dual formation [ dual isn't double the single ]

so as you have a stronger tyre it won't need the same inflation pressure
so get the axle weighed when fully laden , then refer to the ETRTO charts for the correct pressure to carry that load for that tyre ; if you can't find that any tyre manufacturer has a copy , but I think it is all still on the toyo website
personally I just cross reference the load index with the load to get the pressure
and also I just fit the correct tyre as laid down by the vehicle manufacturer ....they spend a lot of time and effort to work out the best fitment