When most people buy an auto racing helmet, their criteria is usually something along the lines of how well it fits their head, cost, and possibly the design if that is your thing. But one aspect which few consider is arguably one of the most important: how well a pair of glasses fits with the helmet on.
By design any auto racing helmet will cover your ears and temple, and a full face will, naturally, cover the face as well. Since glasses have an arm and an ear piece which keeps the glasses actually on your face, these two pieces will be directly where the helmet is going to be. How the helmet sorts out this interaction can make or brake your day. And don’t just think this applies to prescription glasses - sunglasses fall into the same boat.
To be fair, as long as glasses stay in place after they are put on, any further complaints are in a way petty. But over the course of several hours, these petty issues can become rather unpleasant distractions. And distractions are pretty much always bad.
I have a G-Force helmet, and my glasses or sunglasses fit, but just barely. There is a break in the foam right along the temple and ear, and into this divide my glasses always fall. Unfortunately, the angle of this divide is not the angle I would normally have my glasses at, and they consequently get pushed up into my eyebrows. That gets old kind of fast. If I pull them out more, they feel much better, but are more susceptible to bumps. And though tracks pride themselves on being silky smooth, there are bumps are racetracks, sometimes to the extreme. In the last season before Lime Rock was recently paved, the bumps coming out of Big Bend were very rough and there were a bunch of them. Quite a lot of real estate in the second part of the turn was bumps. With my sunglasses pulled out slightly, the bumps would cause them to bounce so violently that I literally could not see until I had hit track out and the surface got smooth again. Not being able to see at all is decidedly worse than a distraction.
It may seem silly to try on your glasses when you are trying out helmets, but you’ll be glad you noticed any catastrophic issues at this stage rather than the first time you put your glasses on at the track.