If I switch to a tire that is 7mm larger in diameter (so 3.5mm taller radius) do I just need to adjust my rear shock down 3.5mm? Are there other considerations? I have a Penske rear shock that is adjustable eye to eye BTW.
Technically it's not a 1 to 1 relationship, and it depends on what bike you have. In other words, on some bikes it may be that to reduce the rear ride height by 5 mm, you might only have to reduce it by 2 mm on the ride height adjuster. Just an example...it depends on the geometry/setup of the bike. Maybe someone that's familiar with GSXR's will know exactly. However, that difference won't be that critical. I just put on a tire that was 15 mm bigger in diameter (7.5 radius). I adjusted my ride height by 2-3 mm, and the bike felt exactly the same.
Thanks. Good point about not being a 1 to 1, hopefully I would have noticed that when I went to make the adjustment. I'm just gonna ride it and see if I feel like anything needs adjusted.
You are changing the swingarm angle by adjusting the shock length. If you don't want to change the swingarm angle you can raise and lower the forks to compensate for changes in rear tire height.