Depends...
185 will fit on rims between 5 and 6.5 inches wide.
215s will fit on rims between 6 and 7.5 inches.
So if your rims are currently between 6 and 6.5 inches you could fit 215 tyres, but it would be pushing it to the maximum that would go on those wheels so not really recommended (especially not if you have 6inch rims!).
There would be 3.34% difference in the rolling circumference meaning your speedo would read 3.34% higher than it should.
You'd also have to make sure there is enough clearance so the larger width tyre doesn't hit anything (especially on full steering lock)