# How do old tires degrade? **URL:** \ **Category:** Factual Questions\ **Created:** [March 12, 2000, 7:07pm UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678 "2000-03-12T19:07:00Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![MiXiM](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@MiXiM](https://boards.straightdope.com/u/MiXiM)\ **Post date:** [March 13, 2000, 6:02am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/1 "2000-03-13T06:02:00Z")
I would like to use old tires in my organic garden as landscaping. I would never consider using the accepted standard of pressure treated wood because of the toxic chemicals that will bleed out of it. Then someone suggested that tired may also degrade into less than nice things to eat. Does anyone know what chemicals old tired will break down into? I figure they can’t be all that toxic becase you see serface dumps of old tirs all the time. But then people build picnic tables out of pressure treated wood. Hmmm… * * * ---
**Author:** ![Poto](https://avatars.discourse-cdn.com/v4/letter/p/7ab992/32.png) [@Poto](https://boards.straightdope.com/u/Poto)\ **Post date:** [March 12, 2000, 7:07pm UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/2 "2000-03-12T19:07:00Z")
Well, we don’t lick the tables afterall. You can buy shredded tire as mulching. I think there is some risk of it melting in hot sun. No idea what all would leach out, but the rubber is relatively harmless. ---
**Author:** ![Cowboy\_Greg](https://avatars.discourse-cdn.com/v4/letter/c/7ba0ec/32.png) [@Cowboy\_Greg](https://boards.straightdope.com/u/Cowboy_Greg)\ **Post date:** [March 12, 2000, 10:11pm UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/3 "2000-03-12T22:11:00Z")
[This link](http://www.sare.org/san/htdocs/hypermail/html-home/18-html/0259.html) goes into some detail on the subject. Apparently the big problems with shredded tires is the zinc, which can be toxic to plants, and the sulfur, which acidifies the soil. You may want to reconsider using them. The rubber itself is not a problem; apparently one of the ways that old tires degrade is from microbes eating them. * * * A cubicle is just a padded cell without a door. ---
**Author:** ![SanibelMan](https://avatars.discourse-cdn.com/v4/letter/s/a88e4f/32.png) [@SanibelMan](https://boards.straightdope.com/u/SanibelMan)\ **Post date:** [March 13, 2000, 4:46am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/4 "2000-03-13T04:46:00Z")
I will warn you that our school uses shredded tires around the playground areas, and they stink to high heaven. Just so you know ahead of time. ---
**Author:** ![\_Df](https://avatars.discourse-cdn.com/v4/letter/_/7ba0ec/32.png) [@\_Df](https://boards.straightdope.com/u/_Df)\ **Post date:** [March 14, 2000, 2:00am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/5 "2000-03-14T02:00:00Z")
Also, if you have a serious latex allergy you won’t want to have the tires too nearby…just something to think about. Where do you get your information about the pressure treated wood leaching? Did you just assume, or is there a source? (I was going to sink pressure-treated wood planks around my raspberries to keep 'em from spreading where I don’t want 'em. I _assumed_ the problem of leaching would be minimal - not nonexistent, but minimal.) ---
**Author:** ![Spoke](https://avatars.discourse-cdn.com/v4/letter/s/a88e57/32.png) [@Spoke](https://boards.straightdope.com/u/Spoke)\ **Post date:** [March 15, 2000, 1:13am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/6 "2000-03-15T01:13:00Z")
> [@](#): > > How do old tires degrade? They leer and whistle at shapely young tires. ---
**Author:** ![ASPA](https://avatars.discourse-cdn.com/v4/letter/a/b19c9b/32.png) [@ASPA](https://boards.straightdope.com/u/ASPA)\ **Post date:** [March 15, 2000, 5:01am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/7 "2000-03-15T05:01:00Z")
> [@](#): > > Originally posted by MiXiM: > \*\*How do old tires degrade > \*\* Belittling and Slander are two of the ways (that tires and hubcaps and steering wheels degrade. They degrade one another and then can’t ride away. ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [March 17, 2000, 6:25am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/8 "2000-03-17T06:25:00Z")
My wife likes the [GardenWeb](http://www.gardenweb.com/) forum for gardening questions. You might try asking there. We used pressure treated lumber to frame our garden beds, and I put plastic sheeting between the wood and the garden soil, so any chemicals which leached out wouldn’t get into the garden soil. Supposedly, there is plastic umber,made from recycled food grade plastic, which would last a long time. I’ve never seen it, and it’s supposed to be expensive. * * * _It is too clear, and so it is hard to see._ ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [March 17, 2000, 6:26am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/9 "2000-03-17T06:26:00Z")
That’s lumber, not umber, of course. ---
**Author:** ![Sentinel](https://avatars.discourse-cdn.com/v4/letter/s/fbc32d/32.png) [@Sentinel](https://boards.straightdope.com/u/Sentinel)\ **Post date:** [March 17, 2000, 2:10am UTC](https://boards.straightdope.com/t/how-do-old-tires-degrade/8678/10 "2000-03-17T02:10:00Z")
One thing that lumber companies don’t tell you is that some of the pressure treated wood – the green colored stuff that seems to feel wet for ages, I believe – is treated with arsenic. Yeah, nice huh? Use it in your garden without a barrier and you’ll be leaching a poison into your vegetables. Check with your supplier before buying any pressure treated wood because all such woods have chemicals infused into them to act as a preservative.