Anyone running 285/70 on OEM 17" rims?

[pacofortacos]

I have about 400 miles on a new set of Cooper Discoverer ST Maxx in 295/70/R18 and I also have that squirmy sidewall issue when turning sharply. It almost feels like the rear end is kicking out. Could this be due to the tires being new? A body roll issue with my shocks??

That's the feeling I had with the Michelin Defenders.
Does the Cooper have a soft sidewall - when not inflated.

There are significant differences in sidewall stiffness when not inflated, I have tires that I use on my trailer (light truck tires) that have a stiff sidewall that I can barely deflect when pushing by finger. By contrast, the Michelin Defenders would deflect almost by just looking at them. LOL very slight exaggeration

 

[osprey ram]

Have 09 1500 4x4, 285/70-17 on stock aluminum wheels. BFG KO2, 42psi frt. 40 rear. Lower psi gives the feel ya describe.