How thick can you go without cutting anything ??

[flee]

can I fit some 18x8.5js ?? has anyone tried?

[ipd]

https://tiresize.com/metric-tire-conversion/

Not sure if you're asking about tire or rim size. I have 18x9 rims on mine.

[flee]

was thinking about getting some after market rims for off-roading

[ipd]

If you're serious about off-roading, 18's aren't really what come to mind. 15 or 16's is what I'd go with. Even the stock 99 rims.