Try www.camskill.co.uk for tyres, www.4x4tyres.com for rims. You can get modular steels new for £35 each, or ebay any Japanese 6 stud wheels except Suzuki, and Daihatsu. I have hilux alloys both for £50 all 4.
http://www.alloywheels.com/tyrecalc.asp
Try above link.
I have 31 10.5 15 US which is 31" total hight, 10.5" tyre width, 15" is a rim. to UK it is 265 70 15
Hope it helps.
I had simillar problem.
Check if your trosion bars are adjusted equally.
Measure from the top of the tyres to wheel arch parked on the flat.
It did solved my problem.:thumb2
I have 2" lift on the back, and adjust torsion bars at the front.
2" Lift springs from ebay about £80. Removed front stabilising bar.
31 10.5 15 bf tyres.
It did lift in total aprox 100mm (4").
Any one intrested in day of greenlaning in Surrey Hills in next few weeks.
There are few nice lanes up there. Enought for all day with the barbeque.
Let me know.:thumb2
Regards