I have searched around & found conflicting info so can anyone tell me that knows for sure through experience if 245/35/19 tyres 8.5 inch wide rims with +40 0ffset will go on a TJ lowered about 20mm or a bit more i did'nt lower it myself it was bought that way so it's a guess.
Thanks in advance.

I am running the same size tyre on 8" rims with a 42 offset with no problems

I am running the same size tyre on 8" rims with a 42 offset with no problemsThanks Mate I appreciate that.

The magnaforce, that's a difference of approx 8mm between those two specs, yours would come out 8mm further towards the guards.
May still fit though just not 100% because specs on mine are different again, sorry