I'm pretty sure tyres have a statutory warranty of 5 years from purchase date (I know this to be the case with my local tyre place ) , would be having a chat to the retailer, if no luck might be worthwhile contacting the Tyre and Rim association.
Looking at Tracks4Aus there is a track about 2-3 kms west of Katoomba along the highway (looks like it is called Nellies Glen ) which heads down to Euroka which then crosses the Cox's River and heads to Black Range which then takes you to the Jenolan Caves Rd.
Doable ? no idea but it is on the map.
You can get a tool known as a nylon strap oil filter removal tool, it works with the use of your half inch socket, this is the only removal tool that has never let me down. about $20 from repco supercheap etc