So I checked out the Kenda website and contrary to what I'm finding in some Internet ads from bike shops, this has what Kenda call their STANDARD RUBBER COMPOUND. Can't find any references to a TPI count anywhere. Weight is listed as 480g, pressure rating as 50-85PSI. The most surprising thing was that it was listed under WHEELCHAIR tires and not BIKE tires.
http://www.kendatire.com/en/home/whe...s/kourier.aspx

Translation? Probably an inexpensive tire supplied as OEM equipment to minimize costs. The weight is OK but swapping those over to some bike specific slicks with a TPI count over 60 will probably be a lot more interesting. Those are probably about 26TPI and lets face it - speed and rolling resistance probably aren't as important in a wheelchair as on a bike. Even for those guys that race wheelchairs. High performance and racing tires can have thread counts over 120TPI but there's absolutely no point going that high.

I run Schwalbe Marathon Supremes myself - you may find them a bit expensive. On the other hand - I find the straight Marathons overly heavy. Continental, Schwalbe snd Michlin all make some good tires, but so do a few other companies like Specialized and Kenda. The Specialized Nimbus is excellent. To get a reasonable 'upgrade' you'll really just have to go for as slick a tire as possible and be prepared to spend $25 to $45 instead of $10 to $20.

That Thick Slick you posted looks just fine.