What shoe size would be appropriate if I got wide (2E) shoes?

My entire life I've always worn shoes about 1 size too big because they were comfortable on the account of my wide feet. My foot is just under 9.5" long, but I've always worn 8.5 shoe size which should accommodate a foot length of 10 3/16", but they had just the right width, and I've never had a problem with the extra wiggle room. I'd wager I could make a size 8 work if needed (e.g. renting bowling shoes).

I have no experience with wide shoes, so I have no idea how they would fit, and I really don't have the time to sample shoe sizes at a store. Best I can measure, my foot is about 4" wide, but that should have a fair margin of error given my lack of skill and equipment (household measuring tape and straight edge).

Could someone make a suggestion?