Interestingly enough, bigger brakes don't necessarily mean better braking performance, as indicated by both the times and the braking distance! What is most important is first sufficient braking power, but once that's achieved, it's probably actually the front-rear braking bias. What I've found more recently is that, at least in this build, maxxing out the disc size rarely makes for faster times around the track.
What Leo's saying about the tyres is actually the profile (the ratio of your sidewall height to the width of the wheel). Larger rims on the same size wheels means a lower profile, but there's a minimum profile for each tyre, otherwise it just won't structurally hold up (and this depends on the tech year). So if you had smaller rims, that would increase the profile of the tyre, which allows you to use wider wheels. When it comes to the driving wheels, wider is generally better, because it means more contact with the ground and better power, and when it comes to lap times, that's probably more important than sufficient brake size, because really, most of the cars here are pretty light and don't need huge brakes anyway. Besides, stopping fast is not that useful if the car doesn't go fast to begin with
