Naked Science Forum

General Science => Question of the Week => Topic started by: Adam Murphy on 10/05/2021 15:12:10

Title: QotW - 21.05.10 - Could dog urine dissolve a tyre?
Post by: Adam Murphy on 10/05/2021 15:12:10

We've received this burning question from Trent:

"I just got back from walking my dog. Now, about a block from my house, there's a trailer that's been parked there for a year or two and every time we walk by, the dog pees on the same tyre. It got me thinking: Urine contains uric acid, is that strong enough to eat through the rubber in the tyre? If so, how long would it take?"

Any thoughts?

Title: Re: QotW - 21.05.10 - Could dog urine dissolve a tyre?
Post by: alancalverd on 10/05/2021 18:02:47

Let us know when you see the tyre cords.

Title: Re: QotW - 21.05.10 - Could dog urine dissolve a tyre?
Post by: Bored chemist on 10/05/2021 19:34:27

Quote from: Adam Murphy on 10/05/2021 15:12:10

Urine contains uric acid,

It contains lots of things.
Uric acid is a very weak acid.

Title: Re: QotW - 21.05.10 - Could dog urine dissolve a tyre?
Post by: CliffordK on 10/05/2021 20:28:07

Urine will also degrade into ammonia, a relatively strong base.

Many types of rubber are relatively resistant to aqueous solutions, but are susceptible to organic solvents.  But, the kidneys filter water soluble molecules into the urine, so perhaps it would be OK.

Tractor innertubes are routinely filled with some type of salt water, and the tubes last just fine (but don't do that with tubeless!!!).

I'd be more concerned with the impact to associated metals.  So, most tires will have some kind of steel bead encased in rubber, but if that gets exposed, it could corrode and compromise the tire very quickly.

Steel or aluminum rims could also be damaged by urine.  And, if it is a tubeless tire, rim corrosion could cause leakage. 

Tire valves, if exposed, can also be susceptible to damage.  Easily replaced, but a pain if they leak.

Title: Re: QotW - 21.05.10 - Could dog urine dissolve a tyre?
Post by: alancalverd on 11/05/2021 10:52:22

Buzz Aldrin famously told a story in response to the question "what have we really achieved?".

Every day as he drove to work, a dog ran out of a driveway and chased his car. He wondered what would happen if the dog caught the car, so one day he stopped. The dog ran out, urinated on a wheel, and ran back to his yard.

"Well, Jay, we've pissed on the Moon."

Title: Re: QotW - 21.05.10 - Could dog urine dissolve a tyre?
Post by: nudephil on 17/05/2021 18:02:49

Thank you all for your comments. Here's the finished segment, as broadcast last night: https://www.thenakedscientists.com/podcasts/question-week/can-dog-wee-dissolve-rubber-tyres

I wish I'd noticed the Buzz Aldrin story - that would have made it in! Was too busy making wee jokes.