Firstly, we recommend that you visit your local Sweet Protection dealer and try the different helmet sizes.
There are two things that could happen if you purchased the smaller sized helmet
1. You could possibly get a very snug helmet and might not need to adjust anything, by adding extra pads.
2. The helmet could be too snug, hence tight, creating pressure points around your head. Depending on your heads shape.
Choosing the slightly bigger sized helmet would be the better choice as in all our helmets there is extra padding included. This means you can pad out the helmet to suit your needs, in addition to the Occigrip, this creates a very good fitting helmet.