The Conti Gatorskin 28c model is the default tire for most go-fast tandems. In the tandem world with a team weight of around 300 lbs, a 28c tire at 120 psi is pretty much as standard as a 23c tire at 100 psi would be for a single bike with a 150 lb rider. The Gatorskins are one of only a few 28c tires that are officially rated to handle that pressure, which is why they are so popular in the tandem world.

We (a 300 lb team) have done over 7,000 miles on our tandem with 28c Gatorskins, and I can only recall one tire-related issue, which was a rear pinch flat when going down an extremely rough unpaved road that we probably shouldn't have been riding that bike on anyway. At all other times, the tires have never let us down. The Gatorskins are also reasonably hard-wearing, and so the rear tire lasts a decent amount of time even on the tandem.