235/85 tyres low PSI in sand. 7" or 8" wide wheels?

Look at the manufacturers website.
All tyres have a max rim size value. That values is advised by the manufacturer.

Contact the tyre manufacturer.. If they don't know then nobody does. There should be a customer information number or email address on their web site. They should also be able to help with the correct pressues and how to adjust them according to load.

Tyre design is a lot more complex than it looks. I remember seeing a 235 on a six inch rim as standard equipment on an earlier 4wd, possibly as far back as the 1980s. It may have been a Pajero but I don't think they were as big or as heavily constructed as a 235/85 x 16.

There was some information on the Dunlop site about wheel widths and their effect on tyre temperature. It may still be there. As the wheel gets wider or narrower for the same size tyre, it moves the designed flex point of the sidewall either towards the bead or the tread. This has a an adverse effect on the tyre temperature.

Sneaky Pete has the numbers. Tyre manufacturers will have the min-max wheel width

I'm running 255/85/16 on 7" Toyota rims.

I have run 235/85s on factory 7" rims for years now , no issues at all and down to 12psi in sand
Came from the factory with lower profile 235s on 7" rims

7" is best size for that tyre width.

I ran 7" trak 2 16 inch wheels with my 235/85 on GU patrols.

I ran 235.85R16's on both Toyota std split rims and Sunraysia copies 7" steel rims, with no dramas, on an '02 HDJ79 ute.

They are a good choice, because in an emergency you can run a mix of 235's, 265.75R16 or even 750R16, just to get home.

Bob

8” spread the walls out wider and expose them to possibly more sidewall damage, and probably no other benefit, the wider rim certainly doesn’t change the tread width. IMO
Cheers

Thank you for the responses. I've decided to stick with my stock 16x7 wheels for the time being. I emailed BFG and had the following response:

There is a range of rim widths which are approved for use when utilising the LT235/85R16 tyre dimension.

The range of widths are from 6.0 to 7.5 x 16. The preferred rim width is 6.50 x 16. The use of an 8.0 x 16 rim is not approved and would void any warranty. The most common fitment would be 7.0 x 16.