I have noticed that the lettering on my tires has turned yellow and now is turning brown. I have scrubbed on them with simple green and bleachwhite and nothing seems to work. Yesterday, I used a little orange/pumice hand cleaner and it worked but took like 5 minutes per letter. I do not have the patients to work them all They look like crap though. Does anyone know what causes this? these tires are about a year old, maybe 1,000 miles. Does anyone have any great ideas for getting them white again that does not involve me killing myself?