NASCAR actually mandates the bracing for crash safety. They utilize a 1/4" window which is much more rigid of course than the 3/16" that we recommend for most street and drag applications. But there truely is no need to go any thicker than 3/16" for 95% of the vehicles out there. However with that said if you are running in a sanctioning body that requires 1/4" such as some road race organizations we can accommodate you.
