As long as you have a cell phone and a friend or partner who’s willing to pick you up, go as low or as high as you want! I’ve just gone up or down 5psi at a time for a few rides to see how things feel, and eventually settled on a range that I’m comfortable with, which is about 78-85psi on my effectively 32mm front (28mm Conti Ultra Sport 2), and about 90psi on my effectively 28mm rear (25mm Conti GP4k - my last one). Both are higher than is ever recommended, but it’s what I like, and isn’t that what matters?