Non slip manhole covers

[ryandalling]

Wouldn't it be great if they were on all the manholes??  I have had too many pucker moments hitting manholes in the rain, and even worse while cornering.

http://www.manhole.co.kr/eng/product-non-slip-manhole-cover.php

[Porsche Monkey]

Doesnt look like they will work for motorcycles.  Only says cars and bicycles.

[Jarvicious]

Doesnt look like they will work for motorcycles.  Only says cars and bicycles.

^^

I wonder how well they'd wear though.  If it's nothing more than rough cut steel, it would probably go bald a lot quicker than even a standard manhole cover.  So then, instead of a moderately textured cover you've got nothing more than a finely honed, wet piece of greased lighning waiting for you to ride over it and simply tap your front brake the littlest bit.