Roosterman17

I recently purchased a 2006 GL500 (in NSW, Australia) and have a few questions.

My GL is fitted with the standard Pirelli Scorpion 275/55 R19 M&S tyres. I've been off-road a few times but the relatively low profile and air suspension makes for a very bumpy ride in off road mode, and I'm nervous about puncturing the sidewalls. I've been airing down to 27 psi on rocky sections, which helps, but I don't know how low I can safely go with this size tyre. Does anyone know if the 275/55 R19s can be safely aired down to around 20 psi?

I've tried to find some more serious all-terrain tyres to fit, but haven't been able to find any all-terrain tyres in Australia in 275/55/ R19. Is anyone aware of any all-terrain tyres that fit this size? I note that all-terrain's are available for the GL320 if it's riding on 18" wheels, but 18" wheels won't fit on my GL500 because the brake rotors are larger.

I've also been considering fitting a larger tyre size (e.g. 285/55/ R19) but I can't find any all-terrains in this size in Australia either. On the plus side, I have managed to source some snow-rated tyres in 275/55 R19 (Nokian WR SUV4, from snowtyres.com.au).

I also want to fit some rated recovery points front and rear. Does anyone know if there are any available in Australia to fit the GL500?

I also want to fit a Rhino mesh rack to the roof so I can carry a full-sized spare wheel and tyre, as there's not much room in the boot when it's fully loaded with gear for the family. My owners manual states that the roof is rated for 90kg load, so a single wheel and tyre should be ok. I understand that carrying a spare on the roof isn't great for wind noise, handling, fuel consumption, etc, but it seems like the best option if the boot is full. Does anyone have any experience with fitting a spare to a GL roof rack?

Thanks, much appreciated
Mark