I test drove an ACE this weekend and I fully agree that large heavy tires will kill this machine but I think there are a handful of tires that are light enough to go to a 27-28. I'm going to wait a little while to buy one for a few reasons, mostly $, but I also want to see what works and what doesn't. Right now I'm thinking 27" zillas on machined 14" ITP SS212. Zillas are the lightest 6 ply tire I've found and I love the 30's I had on my Teryx and now teryx4. Sadly they aren't designed to carry the weight of my VERY heavy Teryx4 so I'm going to a 28" 8-play radial. On a lightweight machine like the ace tho, they will be perfect.