How can I attach a none slip rubber mat to a tub liner

Maybe try Sikaflex and the primer that can be used with it........... I am sure that others will come up with other possibilities.

If its a heavy one and is cut to shape it will probably just sit there.
Putting screws through it will just tear holes in it if it moves.
Did to the one I put on top of the drawers in my Cruiser

Plain old silicon, non acid cure preferably will just about stick anything to anything. Stopping water laying under the mat might be an issue though, if the crud gets trapped between the mat and the liner it may get smelly etc.

Tub liners are made from Polyethylene.
It is a bit like gluing something to a candle.
Essentially, nothing will stick to this stuff with any life certainty. It is specifically excluded by Sikaflex.
I would consider hot air welding some reinforcement patches to the tub and then using mechanical fasteners to them.

Cheers,
Peter
OKA196 Motorhome

Boob Boo - A good quality Silastic will probably suffice for all intents and purposes - but if you want a stronger bond, try 3M's Scotch-Weld PR100.
You will need some 3M AC77 primer for the polyethylene to get a proper bond.
This stuff is a cyanoacrylate product and it bonds on contact, so ensure your alignment is correct before positioning.
This adhesive also requires a close tolerance fit to work properly (maximum gap .015mm), whereas Silastic will tolerate large and uneven gaps.

3M Instant Adhesives

Cheers, Ron.

I just read your other thread, all that "red paste" is probably grinding away between your tub liner & the tub, if it was me I would throw the tub liner away, I have seen some very badly rusted tubs under liners"

Boo Boo I had the same issue on a couple of my utes and I just used a normal rubber ute mat cut in to the floor shape and they are heavy enough to sit down under their own weight and don't move around
I bought my Falcon one from Clark Rubber and on my Hilux used a genuine rubber mat, just had to trim it a bit smaller to allow for the poly liner

hi boo-boo
ive own 3 dual-cabs since 1986 and ive never bothered with tub liners
I have just only ever gone into clark rubber and bought a length of multi-rib rubber matting 1200 wide and length to suit
its tuff and lasts for years doesn't need adhesive and stops things sliding around
take out and wash when need be
also use a piece in 6x4 trailer at times
tub liners get dirt and moister under it and it will eventually cause rust that I have seen as proof and some one else also mentioned
the multi rib matt also stops road noise and drumming into your cab particularly if there is a fibre cab attached to the well-body the cost will be minor compared to a tub liner
my two bobs worth from personel experience
cheers

Boo Boo,
my experience with tub liners is very negative. As stated before water gets under the liner by either sweating or ingress and sits. The result is severe rusting.

I have a liner in my tub but I have a canopy and roller draws. I cut the liner out on the bottom under the draws and coated the sides of the tub with soft seal before reinstalling the modified liner. Another thing is at the front of your tub you may find 2 holes high up on the tub each side. I suggest you seal these with sikaflex.

In your situation I would remove the liner. Soft seal the front and sides. Cut the liner with a jigsaw so that it only protects those side areas and smooth the cut edges with a cheap deburring tool and reinstall.

Then I would place a removable mat on the bottom of the tub so you can check and dry it out if necessary.