Most likely to help keep stuff like brake dust from eating it off too soon.

 

Dumb question...does dirt/brake dust actually eat it off (ie chemically react w/ it), or does it just depost on top of it, reducing the shine? Cuz I thought it was the latter...

 

I think UV light degrades any tire shine and the tire surface, making it look brown. This is the rubber itself degrading. The blackness comes from the carbon black, which protects the bulk of the rubber from UV light, but obviously not the rubber at the very surface. Of course, just a little UV degradation makes it look brown, so it's sort of a hard battle to fight.

Take a peek at your front wheels vs. the rear wheels - the fronts generate much more brake dust, and yet they tend to brown out as fast as the rears. As well, guys like me who don't drive it much will see the fade to brown even if the car isn't driven.

Dave

 

Cool...good to know. Thanks.

 

I pressure wash the tires every week.

This way it "freshens" it up.

 

You're crazy lol. I've pressure washed my deck before, and it can straight up take off a LAYER of wood if it's close enough. Holding a pressure washer near my car will generate the same reaction as holding a flame thrower: I'd get ready to kill you lol. That stuff can strip your paint, and who knows what it can do to rims and the tire structure. Look on the sidewall. There are thousands of micro cracks in it as it is. No reason to use something under a HUGE amount of pressure that can further weaken it... That's just my opinion.

 

I pressure wash my powder coated wheels, doors, sunroof, fenders and the rest of the car.

at 1600psi it's nothing.

Look at the paint and tell me that doesn't look like 250k~ miles.

 

My fronts brown MUCH quicker than my rears (on my DD M3). If you don't drive the car often, then yes they will brown within about same duration (as you have just natural UV acting on them more than anything else). If you daily drive the car, the fronts will brown much quicker.

 

Well there you have it, both make a difference. :o)

Dave

 

ill have to try it, nothing like having you car alll claean and then when you get out from were ever your going you have this dirty streaks comming down your wheel pppppppppiiiiisssssssssssssssss you off sometimes