Tyres plus wide rims
Indeed you could fit those tyres – and be wrong! At 28mm they’re the narrowest tyres compatible with those wide rims, so whilst they’ll fit, they’ll adopt a somewhat flattened profile, unresponsive to bumps in the road, so they’ll feel even harder and take more effort than they should. To deliver their promise of reduced rolling drag, narrow tyres need to be on narrow rims. If you can pump a wider tyre up to the same pressure, it will actually roll easier!
It’s not so much the weight as the stiffness of puncture-proof ‘Plus’ tyres that make them harder and slower than non-Plussed. The thick layer of extra rubber leaves less sidewall to flex and ‘Plus’ tyres become even less compliant in narrower versions (and more difficult to fit to rims) due to the shortened amount of flexible sidewall. I would not resort to ‘Plus’ tyres, even in winter, unless I had a serious puncture problem with thorns, flints or glass on my route. But if I did, I would fit wide ones and pump them up really hard.
This was first published in the February / March 2013 edition of Cycle magazine.