Why doesn't the road lose its thickness to the tyre? From this source, on average a rubber tyre loses $2$ atoms thickness per revolution due to the friction with the road.   
Do these atoms/molecules that were peeled off the tyre get absorbed by the road? Then would the road increase in thickness due to this? If so, why doesn't the road lose it's thickness to the tyre instead? Thus making the tyre increase in thickness over time... 

 A: Others have noted that roads wear - an example of softer materials wearing harder one is liable to be useful.
If you look at centuries old stone stairs in Europe it is common to see a double indent shape worn by foot traffic. In the stairwell of the Leaning Tower of Pisa the stair indentations made by foot traffic have been filled with some protective substance (possibly many times) and are on their way once more to being worn into a double indent. 
While both stairs and shoes wear, the rate of wear of the stone is no doubt such that the amount worn off in a climb is minimal - I'd doubt that you'd end up with a visible amount of stair dust coatings on the bottom of your shoes. 
I took this picture in the 'Leaning Tower' in July 2003. You can see both the wear patterns in the stone and the added protective material:

Detailed crop. Larger image 

A: Both the tire and the pavement wear from the contact between the two.  The road will take significantly more damage if the tire has rocks stuck in the treads, but even in a "pure system" of perfectly clean rubber tires, the road suffers erosion just like everything else.  
The folks who commented on the hardness or density of the pavement are right, but they left out the part where silk can be used to sand hardwood.  It may take a really long time to make a visible dent in the harder surface, but your inability to perceive something doesn't make it nonexistent.
A: Wheels sweep the road and the car creates enough wind to move most sizes of particles to the sides of the road. The rubber and road aren't comparatively adhesive enough to build up.
Sun and frost ( freeze thaw weathering ) are a lot more forceful than tyre contact.
Chemistry formulas may demonstrate that if the road grit's atomic bonds are a thousand times stronger than rubber, they will only wear out from impact with stones caught in tyres rather than the rubber itself.
Sharp bends in the road recieve a lot more physical force than straights and can wear multiple times faster.
A: I believe it has to do with the hardness of the tire vs the road. Hardness is a measure of resistance to wear and the material of a paved road is generally harder than the material of a tire. So the tire will wear before the road with a net transfer of material from the tire to the road.
Hope this helps.
A: Anyone who has lived near a major thoroughfare knows that tire wear creates rubber dust that gets spread around everywhere. In some parts of Los Angeles, the residents have to hose off the sidewalks every day or so in order to prevent that dust from being tracked into their homes. Some of it also gets friction-welded into the surface of the road itself, leaving skid marks that are plainly visible. 
Road surfaces themselves also lose material to the passage of tires. On concrete roads, the tire scrubbing action rubs away the mortar between the pebbles and after a while the pebbles become unsupported, and they too become dislodged. 
The road material does not end up accumulating on the tire surface because the tire surface is being continually worn away. Any road material that might get embedded in it is thereby shed loose along with the tire dross. 
A: It can be the other way around too, it is dependent on the modulus of elasticity of the materials, if the road has higher modulus of rigidity then it will not break easily and a large amount of shear stress needs to be applied in order to do so , equal stress can cause different effects on different materials, According to IS:456 the modulus of concrete is 5000√(fck), MPa , where fck is the characteristic compressive strength of concrete whereas rubber has modulus of elasticity 0.0003GPa so when the two surfaces interact rubber loses more.
In regards to the other question, yes the thickness of road will increase but in a non uniform manner. Thanks and regards
