Welcome to the forum
What model Navara do you have?
Wheels is one thing but buying tyres can be the issue. Depending on which state your in , you have different regs on max sizes. In the ACT we are only allowed a maximum of 50mm increase in size. So on a D40 ST-X the factory tyre is a 255/75/R16 and legally we are only allowed to go to a 265/75/R16 or a 265/70/R17.
Offroad tyres will generally last way longer than street tyres. So for instance a street tyre may last you 40,000kms where an AT or All Terrain tyre will last you 2 or 3 times that many kms.I have seen people with BF Goodrich AT's getting over 100,00kms on them.
The other thing to think about is as a general rule the bigger the dia of the wheel the more the tyres will cost.