I'm looking at picking up the Carbondale Topstone 105. It uses WTB ST i23 TCS, 28h, tubeless ready rims. The bike specs with a 40mm gravel tire. I'm wondering what the smallest tire size/spec I could swap out without having to change the wheels. I'd really like to make this bike a solid road bike when the need arises. Any suggestions/comments/help would be greatly appreciated!!!