Richard

Car heater or coolant hose ought to work pretty well if a suitable size can be found.

I've built softer faced rollers using both with reasonable success in the past. Albeit running on ordinary surfaces, not the business side of sanding belts

Abrasion will be very slow so long as the belt surface resilience is such that the abrasive grains "cog" into the material rather than slip. If the sanding grit slips across the roller surface it will wear rapidly. If it "cogs" into the soft faced roller it is basically just deforming it a bit around the sides of the upstanding abrasive grains so the wear mechanism is mostly due to differing shapes and spacings of the grains interfering with the cogging action.Think rack and pinion with rather worn and not particularly accurate pinion still turning easily on its bearing. Normal abrasive action is more like what happens when the pinion bearing is pretty much seized. The pinion teeth get wiped out quite fast.

Clive

Agree with Clive car heater hose, available in a range of sizes, I had to do a temporary repair at work where some short rollers for guiding newspaper inserts along a conveyor wore out and replacements were on back order from Germany. I used a blue silicon hose from a supplier of kit car parts Car Builder Solutions ( probably also available on Ebay), available in straight lengths, the wall thickness is more constant than the cheaper black stuff, and in this situation doesn't leave black marks on the newspaper inserts. Small grooves in the steel roller under the hose, bit like circular knurling, and sliding the hose over the roller after heating in boiling water to soften , all of the sleeves stayed on ok. Got some brownie points at last for that!. the blue silicon may be a little soft for running on an abrasive belt, the standard black hose should be ok for your application, pretty tough stuff.

Richard

I've been trying to remember how much radiator / heater hose stretched when I used it tyre fashion many years ago. Unfortunately the nearest thing to a useful recollection is that I made the base diameter close to, or perhaps a touch larger than, the ridge formed into the hard connecting pipe to stop the house slipping off once the jubilee or equivalent clip had been done up.

On that basis 3 or 4 mm stretch on your 35 mm ID hose doesn't seem unreasonable. Whether it will hold purely by stretch or whether it will need adhesive I know not.

One of those "tried a number of things" jobs which I was glad to see the back of and fairly resolved not to do again in future if at all possible.

Pushing heater hose in steel tubes with suitable mounts welded on as the basis for stiff hinges and home brew anti vibe efforts was a different matter. Used for a number of things and well up too the top of the "works well" list.

Clive