Hi,
In answer to Sebster80, I think you will find that tyres for 4x4's have re-enforced sidewalls, due to the extra lateral (rolling sideways) forces on the tyre wall (high center of gravity) It's the same on my people carrier, you have to have the re-enforced tyre. If you don't, and you have an accident, a sharp eyed insurance assessor is likely to notice, and we know how that will end . . . :eerrrmm:
When you say "passenger tyre" that will be for a car only, not a 4x4. It doesn't matter if you are going off road or not. There is probably more strain on the sidewall going round a curve at 70 mph than off-roading at walking speed.
Hope this helps.
Regards