In reply to Siward:
Not tried ust on a road bike, but on an MTB (with admittedly much lower pressures), when the rim is perfect (straight and very clean) a new UST tyre will go on so well that it won't leak at all and it'll be a bugger to get off again. In fact I rode my mtb a month before thinking "time to go tubeless" and discovering it didn't have any tubes or sealant.
Even the smallest amount of dirt or dink in the rim and it wont work without sealant
However I suspect at higher pressures or with thinner walls, a certain amount of seepage is expected. The tyes now on my mtb would leak a bit, but as soon as the sealant goes in it sorts it.
Just remember to go for a small ride after adding sealant to really spread it well
Post edited at 19:14