Potholes and tire pressure...

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After stoppng to help a young lady with 2 flat tires, front and rear right side, she hit a well disguised crater in the wet road, HARD. Looked like a puddle... like about a million others...

I was looking at my tires, a 55 series winter tire, and wondering if I should ...

1) Pump them up to nearer the max pressure on sidewall in the hope that if I hit a nasty one, maybe the pressure will help the tire / wheel survive... max psi on these tires is 50 psi...

2) Air down a bit in the hope that having some "give..." might be better for the tire / wheel... they are a narrow 55 series, so the sidewall is on the short side...

Stock recommendation is 33 f / 32 r.

Not sure ANYTHING would have prevented damage to the victims car, except maybe a 35 inch truck tire ...

Thoughts...?
 
Originally Posted By: geeman789
After stoppng to help a young lady with 2 flat tires, front and rear right side, she hit a well disguised crater in the wet road, HARD. Looked like a puddle... like about a million others...

I was looking at my tires, a 55 series winter tire, and wondering if I should ...

1) Pump them up to nearer the max pressure on sidewall in the hope that if I hit a nasty one, maybe the pressure will help the tire / wheel survive... max psi on these tires is 50 psi...

2) Air down a bit in the hope that having some "give..." might be better for the tire / wheel... they are a narrow 55 series, so the sidewall is on the short side...

Stock recommendation is 33 f / 32 r.

Not sure ANYTHING would have prevented damage to the victims car, except maybe a 35 inch truck tire ...

Thoughts...?
A little under stock, maybe 5 pounds, IF you can remember to air up when doing highspeed driving. Blowing it up will just make it harder and provide less cushion. Maybe even crack an alloy.
 
Most recommendations I've seen suggest to just run the normal recommended PSI, not higher and not lower.

Also it's important not to have your foot on the brake while hitting the pothole - that just shifts the vehicle weight onto that front tire and makes the impact worse. Better to glide over it instead. Sometimes easier said than done, I know.

But any rim/tire can become a victim - it's just a matter of high enough speed and big enough pothole.

http://www.pottsmerc.com/general-news/20140122/aaa-gives-advice-on-how-to-avoid-pothole-damage

I used to have 205/55/16 winter wheels/tires on my old A4. I did bend a rim on a pothole once.

Wife used to have a c300 with 225/45/17 tires. Some of the rims were so bent, they wouldn't hold air for very long. That's when I convinced her to just buy a truck.
smile.gif
 
If you run over stock pressure it will just beat on other parts of your car-- struts, strut mounts, wheel bearings, etc. You'll get slightly less life and blame it on "darn chinese parts".
 
This is stating the obvious, but speed plays a big role here. If you can, *slow down* when you're on a stretch of road that looks pot-holey. I recognize most of us won't or can't, depending on the circumstances.
 
I blew out a 215/60/15 once on a pothole. While changing the tire, someone else hit the same pothole and also blew out their tire. There's not much you can do except slow down. I have some 245/40/18's now so I bet it's just a matter of time before a tire or wheel gets blown out. Back in the day when I had 80's or 70's or even 65's, I never blew out out a tire on a pothole. Just one of the drawbacks of low profile tires.
 
On the bright side, at least most insurance companies will pay for a damaged wheel - minus any deductible. GEICO bailed us out twice from pothole or sinkhole damage.
 
Yup-the picture of deteriorating roads and these goofy aspect ratios is like the 'perfect storm'. I've been told by the tire shops that it's mostly driven by 'styling' and marketing with engineering taking the back seat=I don't like it much!
 
Indeed a fine balance between pressure to resist the impact getting to the rim bead and yet soft enough to not transfer damage to the suspension. I wonder which is cheaper, a strut or a rim?


My '13 corolla with factory steel 17s rides fairly rough really. I might just get some 16's or 15's and some higher profile tires just to see if it will ride significantly better.
 
Years back, I was denting so many rims on my commute that I started buying replacement rims two at a time from the salvage yard to save on shopping trips.
 
Originally Posted By: HerrStig
A little under stock, maybe 5 pounds, IF you can remember to air up when doing highspeed driving. Blowing it up will just make it harder and provide less cushion. Maybe even crack an alloy.

I find it hard to believe that a little over pressure would crack aluminum alloy wheels, especially in a pothole event. If anything, it would help keep the tire from bottoming out just a bit.
 
There are 2 competing things going on.

1) Bottoming out. That is, compressing the tire enough to completely collapse it. That means that all the give has been taken out and the tire is effectively a band of rubber. This is the more common kind of problem. Obviously the fix for that is more pressure.

2) Impact damage to the tire itself. This is more difficult to describe, but it is where an object is small enough that it doesn't compress the tire enough to cause it to bottom out - think rolling over a jagged rock. In this case, you want the tire to compress more to more slowly absorb the energy - lower pressure. This is not as common as the one above.

So I think higher pressures are the way to go.

So what about the increased damage being done to the other components? Well, the spring rate of a tire is pretty close to proportional to the inflation pressure - and if you increase the inflation pressure 10% (say from 30 to 33), then you've only increased the forces by 10%, and I hardly think that is something one needs to worry about.
 
I usually go with a few extra psi, but I like the ride and handling that way as well.
 
Originally Posted By: AlaskaMike
This is stating the obvious, but speed plays a big role here. If you can, *slow down* when you're on a stretch of road that looks pot-holey. I recognize most of us won't or can't, depending on the circumstances.

If I slowed down enough on the broken streets here, I'd never reach my destination.
 
Originally Posted By: Quattro Pete


But any rim/tire can become a victim - it's just a matter of high enough speed and big enough pothole...

Wife used to have a c300 with 225/45/17 tires. Some of the rims were so bent, they wouldn't hold air for very long. That's when I convinced her to just buy a truck.
smile.gif




Given the condition of many roads, your last point is probably the most realistic...just buy a more durable vehicle, or wheel /tire combo...

In the last 10 years I have bent probably a dozen wheels, and wrecked a few tires as well... I live in an area of the country that sees frequent, extreme temperature swings in winter, as in -5*f or colder one week, then +40*f the next... and the roads suffer, frost cracks and potholes from [censored].

And, after chasing a tire vibration, I was just shown that another wheel is bent... aaarghh. On the back it goes for now.

My bent wheels / tires were ALL 55 series tires or lower... my van with a 225/70/16 tire, and 110000 miles over 7 years, has NEVER had a wheel / tire issue. Not one... knock on wood...

A co-worker bought a new car last summer with an upgraded wheel / tire combo... 35 series tire on a 19 inch wheel...! Looks awesome, but, man is that sidewall short... I told him to be careful, but he had the "won't happen to me..." attitude. Maybe when he prices out a replacement 19 inch factory wheel, he will better understand...!
 
Originally Posted By: geeman789
Maybe when he prices out a replacement 19 inch factory wheel, he will better understand...!

For sure.

On a related note, many car dealers now make add'l money by selling dedicated rim/tire road hazard insurance for those fancy low profile setups.
 
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