I had a look at the 29'er bicycle tires... just a quick search...
The Maxxis Icon Exc 29x2.2 doesn't look like too bad a tire for a motorized bicycle.
Yet it is $65 +
My son really has a preference for the 29'er pedal bike he recently got.
And he makes use of it a lot!
Of course, mostly street riding, but he also does a lot of dirt-trail stuff I am glad I do not watch. He is aggressive and is sure he's bullet-proof.
Never-the-less, at this time, for a motorized bicycle usually run on the street, I am almost sure there are more suitable options, at more reasonable prices in the 26" rim size.
I would NOT buy a 29'er for my own use.
Dealing with the Presta valve is no more than an inconvenience for most riders. Many current pedal bikers are set up for them.
My two cents.