speedo gear

Hitting the exact tire size listed and gear the calc I get is 38.66 so going to be a compromise either way you go. Closer to H22A4's reply though at 39 tooth. Speedo is still going to be a bit off either way you go, but closer to actual with the 39.
Always a brain teaser thinking which way it will go, but I think with a 39 you will show slightly faster on the speedo than you are actually going. Did I get that right? Think so.

Calc shows rpm at 70 mph at roughly 3700-3800 rpm.

Cheers