I own one and have Michelin tires on it, with which I am very happy. They may not be the least expensive tires on the market but you get what you pay for.
Of course not. 19" tires can only be mounted on 19" wheels.
Toyota recommends 225/70R16 size tires.
I don't think there's such a thing as Toyota brand tires.
225 70 16
On a 2001 Toyota Highlander
Yes, with the proper tires is can safely be driven in the sand.
It will cost about $700 to $900 (depending on brand) for four tires including installation. The size for the 20 inch rims on a 2008 Sequoia Limited 4wd is 275/55R-20. I bought Cooper Discoverer H/T.
For the 17" hub, it's 225/65/R17. Not sure about the 16" or 18" hubs.
I installed Toyo Open Country all season radials and live at 7000 feet in the Utah mountains. I also commute each day to 4400 feet. My 2008 Highlander did extremely well with the after market tires versus the original factory tires. You can buy them at Les Schwab Tires out West.
The 2008, 2009 and on Toyota Highlander comes with either 17 or 19 inch stock rims. In case of my 2009 Highlander, it comes with 17x7.5 rims. The best winter wheel set you can get is the original Toyota 17x6.5 RAV4 (no typo here, 17x6.5 RAV4) steel rims (they look like alloy wheels) with the Michelin Latitude X-Ice Xi2 225/65R17 102T (Michelin Item# 21499, wear rating 730) winter tires. Both the RAV4 steel rims and the Michelin tires are one inch narrower then the originals, but they perform better on snow and ice because they are narrower. If the original rims/tires on your highlander are 19 inch, then you need to check with your Toyota dealer to make sure the 17x6.5 RAV4 steel rims will fit on your car before ordering anything. They work on my 2009 Highlander (17" wheels) beautifully.
Both the 16 and 17 inch rim tires have the same inflation rate: 31 psi both front and rear.
Look on the door jamb of the drivers door. There is a plate affixed to the jamb telling you what size tires and what the inflation pressure should be.