It's not so much related to the small upsize in tyre size, it's the increase in down travel which will actually effect your uptravel <-- sounds Odd doesn't it.
Take into consideration teh stock shocks have very little downtravel, it's mostly up!
(with front sway bar disconnected)
Under full articulation with the extra down travel the axle twists in such a way that the compressed spring sides wheel is at such an angle it will come in contact with the front flare metal support bracket which is hidden by the plastic.
For Arguements sake, I have a 3" lift, if i remove my bump stops (2.5") and fit my stocko cheese cutters they will hit under full flex. Only just though.
Take Wranglertj's advice, do the measurements, just get access to someones ramp or something similar, it's what i did to get the best length shocks and right size bump stops. This way you will get the maximum up travel out of your setup and get to know how it all works.. it's a better option than fitting Snake Oil blocks!