I've fixed a lot of lawn mowers that use un-rated fuel line - it's not even SAE 30R7 rated. It's typically brittle and full of cracks. Leave it to lawn mower makers to use a fuel hose that barely even qualifies as fuel hose.
To me, this stuff is a fire risk when the hose rots through after 5-10 years and fuel placed in the mower simply runs out on the ground.
Pep Boys sells 'R7' and 'R9' by the foot and the R9 is a lot more expensive, but it's diesel compliant and obviously better stuff for any gas application.
Steve H. - KE0KNH
Colo Springs, CO
'78 FJ40, '89 FJ62, '98 4Runner