Is there such a thing as a cream or sunblock to slow dry rot of vehicle tires? Seems like a simple problem to solve.
Armor-all claims to do what you want but I’m highly doubtful. I wouldn’t worry about this nor waste the money to “solve” this problem.
When I had my motorcycle, I’d park it on cardboard during the off season. I couldn’t tell you if made a difference, but I had a few people tell me the concrete could dry out the tires.
If your situation is similar (dry rot on the part of the tire in contact with the ground when it’s not moved for several months), I’d start with that.
If this problem is occurring all over the tire, I’d suggest Armor-all, if it claims it fixes it, otherwise any one of the dozens of Tire Shine products or even a light coating of grease or a spray silicone. I’d bet that even some regular car wax would help keep them from drying out. There’s not a whole lot you can do about the treads, but you can do the inner and outer sidewall.
Provided the product you use doesn’t say you shouldn’t get it on rubber, that worst it can do is nothing.
I’d bet even Rain-X would do it.
TLDR, I’m thinking of things that repel water and assuming they’d also keep rubber from drying out. I could be wrong.
Also, anything that says it blocks UV, would probably be a plus.
Having said that, unless you rarely ever drive your car, by the time the tires are dry rotting, it’s likely time for new ones.
AFAIK it’s the UV that destroys tyres. Leaving them distorted by the weight of the vehicle isn’t good either. For the medium term, you need to keep them in the dark, or at least away from direct sun - all you need is some plywood or something to screen them. For long term storage, they need to be off the vehicle and stored, fully inflated, inside out of extremes of temperature and sunlight.
Doubt if they are available for motorcycles, but they make tire covers for RVs that tend to stay parked in the same orientation for long periods.
A coverlike this would work though.
UV, ozone, and oxygen. Common ways to avoid these methods of degradation in general are sunblock (either physical or chemical) and antioxidants. I see products claiming to protect tires but I can’t vouch for any.
I’ve never had a problem with flat-spotting my motorcycles when parking it for the winter. However, my bike is parked on the centerstand for this, so the rear wheel is in the air and the front wheel is loaded with maybe 20-25 pounds of downforce. Possibly it’s different if you park the bike using the sidestand for several months.
Also, I know the OP was talking about cars, but since you brought up motorcycles and Armor-All in the same post, I should point out that using Armor-All on the sidewalls of motorcycle tires is a risky proposition: if some of it drools down onto the tread, you are at risk for a surprise loss-of-traction event on your next ride.
My father was the chief corporate chemist for a large, national tire manufacturer, so I heard about tires all the time. This subject came up and he stated that there was no after-market protectant that was effective in stopping the (inevitable) breakdown of tires. As stated previously, UV is a prime culprit, which is one reason that tires are black (carbon black and other materials are added).
And this is from a guy who worked for months to make orange tires that would match the logo on Gulf Oil tank trucks. They looked great…but there’s more to the story.
When I mentioned the cardboard, that was to prevent the concrete from drawing moisture out of the tires (leading to cracking etc), not for flat spots. I never had a problem with that and my bike tended to stay parked for a year at a time.
And, to top it off, a lot of (mostly non-riders) don’t realize that a good chunk of the sidewall IS tread since you ride on the edge of the tire when you lean to turn.
I’m sure anything that protects bike tires will also protect car tires, but just to be clear and to keep the thread from wondering, I was the one that mentioned motorcycles. I assume the OP was asking about a car.
A Google search finds some people claiming that concrete draws moisture out of the tires, and other people claiming moisture in the concrete is what causes tire rot.
AFAIK, ozone and UV exposure (and plain old excessive age) are the biggest factors in tire decay. Ozone exposure isn’t a problem for most folks, but even plain old atmospheric oxygen will eventually degrade tires, and any vehicle that is driven (or parked outdoors) will also get UV exposure. This is one reason that rot first manifests on sidewalls. Even without UV exposure, rot will slowly occur, and will eventually also manifest in the grooves between the treadblocks, but hardly ever on the outward-facing surfaces of the tread blocks (unless you leave a tire along for a really long time).
Here are some professional-looking websites (as opposed to internet discussion sites) that discuss tire dry rot:
How to keep tires from dry rotting and cracking
STOP THE ROT: WHAT YOU NEED TO KNOW ABOUT TIRE DRY ROT
Bet You Didn’t Know What Causes Dry Rot in Tires and How to Fix It
Wait, what? There’s no water in your tires, so how could concrete “draw out” what isn’t there? And since when did a layer of cardboard create a watertight seal?
Even if you broaden “moisture” to include the oils your tires do contain, this seems nonsensical. Why would cardboard keep oil from getting to the concrete floor? And even if it somehow did that, why don’t concrete garage floors universally show oil stains where the tires rest?
Tire-moisture-repelling cardboard seems a bit like a tiger-repelling rock.