His tires are already airless, that's the problem.

Seriously tho, before you do anything else get a pair of Mr Tuffy liners into your tires. I commute upto 60 miles a day and was having a horrendous time with flats, my worst commute was 5 flats (yes, five ) on my way to work one morning. I was averaging 2 or 3 a week, then I got the liners and have only had one flat in the last 2 months since installing them.

I run Continental UltraGatorskins with kevlar in 700cX28. I was using the Schwalbe Marathon in 37 but without the liners there was no difference in the frequency of punctures. The fat marathons were significantly heavier, didn't grip or corner anywhere near as well, but were quite comfortable. I much prefer the Contis.