What happens to old tires...
 

Today I went to take the jeep and pick up some firewood, and as I got in, something caught my attention. There was a bubble sticking out of the sidewall of the front tire.
http://i56.tinypic.com/9h2mj5.jpg
http://i51.tinypic.com/easg8l.jpg

I don't blame the high inflation pressures for much (running 65, sidewall 55) but rather the old age of the tires.

Bad news: I have to replace one tire, so I might as well replace all of them (they all probably need it). What a shame, so much tread left.

Good news. I get to replace my tires! Now I can shop around for some good long wearing LRR tires. What would you guys suggest?

I must admit that I am not a storehouse of information when it comes to picking a "good" tire. Do I want skinny, wide, bigger/smaller than stock, etc? I don't use my jeep for off-roading, so strictly street tires are fine for me. I plan to put at least another 100K miles on this vehicle.

My rims are 15 inch, and the stock sizes (according to tirerack.com) are 235/75 OR 225/75. The inflation sticker in the glove compartment lists several sizes from P195/75 to P225/75. Well, looks like I get to chose what size I want.

Do I want LT, P, T, or ??? tires? Passenger would be cool (more to pick from, I speculate), and because my truck weighs 3500 pounds (less than many sedans out there) I'll bet I could get away with that. Also, I would not be surprised if the front axle had more than 2000 of that. The back is really light.

I'm thinking that if I get tires that are smaller, I will sit closer to the ground, reducing drag. However, that will also effectively change the drive ratio to be a little shorter.

Comments/suggestions?

I've run many junkyard tires to the ground. I got them because they were cheap or free, depending on. Many of them had wonderful deep tread but sidewall cracking due to age and sitting outside, oftentimes flat (in their previous life on the junker). They are more prone to blowing out the sidewalls than new tires for sure. When a tire is in that condition (bad, deep, or numerous cracks, not little ones) I don't exceed sidewall max psi. I'd say if the other tires have nice tread and lack obvious sidewall defects, to go find another cheap used tire and keep running them all until there are more failures or it looks like more failures are imminent. I like extracting the last mile out of a tire and changing a flat at roadside is no problem for me and I don't mind it a bit- but others need to decide how big an inconvenience blowouts would be for them and what they are willing to pay to increase their odds of avoiding it.

Pure speculation but that looks like impact damage to me. Certainly is badly curb scuffed.

regards
Mech

I put four used Michelin Energy tires on my daughters car for $100.00. One of the nicer used Michelins I picked out ended up having a bulge like that which was a bummer due to the tire had nice tread(the used tire place pointed it out before putting it on my car). They had more than four of them used, so I got another one.

Michelin makes one of the very best tires on the planet bar none, so if it can happen to one of those then it can happen to any tire brand. I never over inflate any tire ever.

Agreed. I get Craigslist used tires for the Clunker, since I'm the only one driving it. The most recent ones are a bit iffy, so I run them at four pounds BELOW sidewall max (40/44.)

You're right about tire height. Shorter will be closer to the ground, but drop the effective drive ratio. So, what's the ring & pinion ratio in that beast? Can the engine pull a little taller tire comfortably? Do you drive on the highway a lot?

Tires are like so many other things on the car: they're a compromise; where do YOU want to put the emphasis? Price? Tire life? Rolling resistance? Cornering? Noise level?

Skinnier tires will have a little less rolling resistance (drag racers use 'em on the front for that, as well as weight; and will 'step down' to a narrower tire in back if they don't need to haul a monster like a 14X32W because it slows the car down to have more than is needed to prevent wheelspin on launch).

Skinnier tires will also wear faster. Some of what you save at the pump, you'll spend at the tire store.

My advice as to what I'd run would probably be a little different than most guys on this forum; I'm not as hard-core about gas mileage as a lot of guys here. I like to be able to drill the brakes and bomb around corners (or swerve around obstacles), and drive everyday through downtown city traffic. As far as I'm concerned, modifying a car I'm going to actually use as a car (as opposed to a toy) to where it makes it less useful as a car... not too attractive to me.

If it were my car, I'd go looking for another good set of 235/75-15 tires, or maybe even see if I could find deep deal on a set of 16" rims and step up to 235/85-16LT (for the height, not necessarily load capacity) tires if I did a lot of highway miles.

And when I buy tires, I try to stay away from those with the huge, high lifetime treadwear ratings. What good is tread depth if the tires' carcasses fail? I like 'em soft enough to grip good; am not happy if they last more than 40,000 miles of in-town use; that means the compound is too hard, and the things are generally not that 'grippy'.

Remember, I tend to be a little outside the profile of the regular ecomodder forum guy.

IMHO LT tires on a 1/2T truck is a joke. Those tires are made for real loads, and are built with tough, heavy sidewall and tread construction. Unless you're putting a bunch of weight in that Jeep... passenger tires will be lighter, ride better, and cost less - if you never use it as a truck. If you haul where you'd be nearing the limits of a passenger tire, then an LT tire is a smart idea.

-Bill

Wouldn't LT tires have less sidewall flex on a lighter truck, giving increased mileage at the expense of ride quality?

Yup.

Oh, and they'll cost more, and weigh more.

Apart from that, they really won't hurt anything; will give very good life. I'd run a set if I got 'em cheap; I just wouldn't pay a premium for 'em.

Kind of like using a Kenworth to pull a little 16' Bayliner boat on a light trailer. It'll work, but it's way overkill.

-Bill

BTW, now I can see all the links in the sig lines! woo hoo!

That's a refreshingly scary picture! It also looks like it could be curbage, but old tires do have weaker sidewalls and are more prone to nonsense like this. I wouldn't want to put 65 in a truck's tires unless they were new and shiny (or maybe my farm truck where they are huge knobby monsters that never really go fast or on pavement but need to be nice and hard).

Definitely go with P tires. LT's designed with good rolling resistance are still not widely available. I have P's on my Odyssey, 4300 lb.

I highly recommend Goodyear FuelMax. They've been worth nearly 2 mpg over the old Michelin Symmetry tires, which are decent rrc already. Also, much quieter, even at the 51 psi sidewall rating.

The improvement in rolling resistance in a tire comes from the tread compound. Sidewall plays almost no role in what can be changed to affect RR.

But even when LT type tires start coming in LRR varieties, the fact that LT tires have high unit loading (high loads compared to the amount of space they occupy), P metric tires will always have better RR.

Based on the most recent study, larger tires have better RR. I know this sounds counter intuitive but that is what it says. I discuss this here:

http://www.barrystiretech.com/rrandfe2.html

Larger tires are less disturbed by small imperfections in the road, which makes sense for lower real-world rolling resistance. That, and taller effective gearing, combined with off-road use are why I upgraded my Jeep from the stock 225/70R16 tires to 245/70R16.

It had no noticeable effect around town (not a lot of extra weight, and taller effective gearing), and a fraction of an mpg gain on the highway at 60mph. The instant mpg on the overhead display reads the same as before most of the time (better RR, but worse aero), but when climbing steeper hills, it typically stays about 1mpg higher than it used to due to the taller effective gearing.

The effects will, however, vary from vehicle to vehicle. In my case, I think the primary reason I saw gains was due to the Jeep needing taller gearing on the highway (with current 3.73 axle gears and larger tires, it turns 1750 at 60mph and climbs any hill without downshifting).

if you have ever faced a blowout or tire separation at highway spds, you might reconsider over inflation :)

I have many times. It goes: flap flap flap flap flap... what's that sound?... FLAP FLAP FLAP... Oh yeah, blowout. Then I gently pull over and change it. No drama. At worst, cold fingers when it happens in winter.

I've done it. No biggie. It was due to old tires, again. That was back in the day when I was running "normal" pressure (lower than placard due to neglect ;)).

Oh you mean YOUR highway speeds. If you're actually going the speed limit or slightly less it's just like Frankly says: "flap flap flap flap.....oh... I've got a flat." This just happened to me recently and coincidentally I was listening to Car Talk on NPR when it happened :). I wouldn't advocate people to do things that make them feel unsafe, but I would advocate for people to gain perspective on what is and isn't safe - put your idea of safeness to the test every once and a while.

I just got both my cars inspected and I was running some junkyard tires on one of them - unacceptable to the inspector. So I just throw a couple of other, better looking junkyard tires on and it passed. I personally love recovering perfectly good stuff from being wastefully destroyed and embrace the recycle, reduce, reuse ethic. I'm glad I've got the personal patience enough to calmly change a tire when it blows out. There's something very cool calm and collected about most of the things I've learned here and practiced on the road - a zen feeling I never ever got before.

Did any of these blow-outs happen in a fairly tight curve ?
Friend of mine had it happen : poof flap screech flap screech flap crash.

It was a worst case scenario though : outside front wheel blowing out

What's over-inflation got to do with it? Under-inflation would be far more likely to cause blowouts. (Due to increased flexing and heat buildup.) But out here in the real world, every one of the few blowouts I've had has been caused by road debris puncturing the tire.

I agree that the risk produced by a blowout or other sudden deflation is a lot higher in an SUV or truck than it is in a low profile Honda Civic or other passenger car. I'm sure everyone remembers the fiasco Firestone went through because their product was used on a defective vehicle (a blown tire should not present a life threatening emergency and if it does, there's a design flaw with the vehicle, not the tire, but Ford's spin doctors got there first). In any case, you might want to look at the NTSB data on rollover rates for your vehicle just for reassurance. If there's a problem, I wouldn't run anything but the best Michelins your money will buy. If there's not a problem, it's because the vehicle was designed to handle problems like flat tires.

BTW, as a sidenote, before the Ford Explorer fiasco, Ford was up against the wall with the Bronco II, which had an even worse rollover record. At the time, the Bronco II was flipping at a rate of 22/100,000 while the Suzuki Samurai was catching all the heat with a rate of 6/100,000. Why? Ford quietly settled hundreds of law suits when the family bread winners were killed and the other spouse needed the settlement to make the mortgage payment. But since the Suzukis were $6,000 cars marketed toward teenagers, mom and dad were still working and they were pissed; thus more cases went to court. Only when the tire failures happened was Ford vulnerable because it was clear they were selling a defective product (the tires, of course).

my highway speeds are most likely the same as yours, 70mph ?
you also might change your tune if you happened to have a 3 yr old (your only child) in the vehicle with you when it happens...
but hey, maybe not.

Nope on both regards.

When I've had blowouts I maybe drifted a bit depending on which wheel but it wasn't very dramatic. Front blows w/ RWD = downshift

Reminds me... yesterday I saw a vehicle adorned with "Baby On Board" signs... sure hadn't seen any of that stupid nonsense for quite a while... was sincerely hoping that fad was gone forever. :rolleyes: As if I was going to recklessly careen into them but D'oh!- spotted those signs and was able to avoid colliding at the last minute, and all because there's a more valuable life in that vehicle.

Also reminds me about threads/posts bragging up new spawn... I've considered starting a "My Sexual Achievements" thread...

What I'm thinking now is that I'll just get a tire of the same (or very close) size to the 30's I have on it now. I know, they are "all terrain" and LRR is not a priority, but I feel too cheap to buy a nice shiny set of tires. Now, at least.

On a side note, my spare tire looks ridiculous compared to the "normal" big tires.
http://i52.tinypic.com/15rxwn6.jpg
The offset is WAY in compared to the fancy-pants alloy rims (that were on it when I got the truck). That makes me think... if I got some skinny tires with rims that have less out-offset, I could make some wheel well skirts... hmmmm.

PS: close observers will note that the tire in question was the front tire. I rotated the back tire to the front and put the spare on the back. I had plenty of time, so I decided to mess with the front end as little as possible. Even though its alignment has only one adjustment, and a solid axle.

Actually, looking at your vehicle in profile, I wouldn't hesitate to use used tires. Compared to most trucks it sits pretty dang low.

You do know these tires were blowing with a two inch hole in the sidewall right? It has happened to me twice. When they blow on an off ramp you would need quite a low center of gravity to not flip. to say the vehicle is defective is a bit of a stretch, it is just the nature of the beast.

Exactly! :thumbup:

My blowout was the right front tire of a Suburban, at 70 mph highway speed. I just eased over to the shoulder and stopped. If I wasn't clear enough before, that was an UNDERINFLATED blowout, not overinflated.

Frank - right on!

I'd say that when a vehicle has such a high center of gravity that it's likely to roll over from a blown tire, then that's a design defect. Kinda like putting the Pinto's gas tank where it's likely to get punctured in rear-end collisions.

PS: And it's not as though the vehicle has to be that high for terrain clearance, since what matters there is the lowest part of the frame/running gear. Look at your typical SUV sometime, and you'll notice that the differential & rear axle is only about 6-8 inches above the road, while the body's jacked another foot or so above that.

You do need that high body line to not get high centered on berms and other obstacles, hence why jeeps and other off road vehicles have short wheelbases. There is a unique strategy you use off-roading to attack berms at a certain angle to not scrape the differential but you need high ground clearance between the wheelbase. Your typical SUV is a body on frame vehicle enabling it to tow more. So it will almost always have a higher center of gravity than a unibody. And if you don't need the ground clearance or tow capacity then maybe a minivan is more your style.

Actually, according the the 60 Minutes episode I watched on the history of the problem with the Bronco II and Ford Explorers, the issue wasn't so much height as it was width. 2" wider and the Explorer wouldn't have had the same issues with roll overs upon tire failures according to the show. The liability emerged after internal documents were revealed that showed Ford was aware of the problem during early testing, but the problems with the Bronco II were a greater concern, so they rushed it to market rather than fix the issue like they finally did when they redesigned the new, lower, wider Explorer.

In any case, my point was not to bash SUV, but rather to point out that if you have a car that has a high center of gravity and is vulnerable to rollover by design, the last place I'd skimp is on the tires. That's just basic risk mitigation.

There's a huge difference between a front tire blowout and a rear tire blowout. Front blowouts are dangerous, causing your car to steer violently in the direction of the flat tire. Rear ones just cause your car to feel a little squirrely.

I've experienced flats/blowouts on all corners, in both cars and motorcycles. I'll bet money that those of you who say "tain't nothin'," all had rear flats.

Nope. Last one I had was left front. Dint even swerve.

I wonder in how many of those "tire caused crashes" the vehicle was going 80 mph with 15 psi in the tires, with 900 lbs of crap in the back or better yet up on a rooftop carrier? And did the cell phone yappin operator even hear the flap flap flap, or was he/she aware of what that noise was, and did they gently slow down to pull over, or did they slam on the brakes and/or violently overcorrect the steering wheel?

Still, there's a difference, an obvious difference with what happens if you're driving a Civic at 80mph and get a blow out and what happens with a vehicle with a short wheel base, high center of gravity, and is too narrow by design.

Here's the facts:
* There will be an estimated 70,000 SUV rollovers in 2002, in which it's estimated 2000 people will die.
* In the 10-year period during which Ford-Firestone related rollovers caused some 300 deaths, more than 12,000 people -- 40 times as many -- died in SUV rollover crashes unrelated to tire failure.
* A Ford Explorer is 16 times as likely as the typical family car to kill occupants of another vehicle in a crash.
* 1 out of 4 new vehicles sold in the U.S. is an SUV, making it the most popular type of vehicle in America. The Ford Explorer is the most popular SUV in the world.
* SUVs had the highest rollover involvement rate of any vehicle type in fatal crashes -- 36 percent, as compared with 24 percent for pickups, 19 percent for vans and 15 percent for traffic cars. SUVs also had the highest rollover rate for passenger vehicles in injury crashes -- 12 percent, as compared to 7 percent for pickups, 4 percent for vans and 3 percent for passenger cars.

While I do have to worry a lot more about the severity of injury due to striking wildlife than the driver of an SUV, you can't ignore the different handling dynamics of SUVs compared to passenger cars.

OK. You want to send it to my PayPal account? Because the two blowouts I've had in the Insight were both the left front, both caused by road debris (holes in the sidewall you could stick a couple of fingers through), both at highway speeds. Both of them were just a bit of thump-thump-thump and a bit of drag & pull. In fact, one was on a freeway interchange - I5 south to I205 south of Stockton - and I wasn't even sure at first that it was a blowout, and not just a stretch of typical California pavement :-)

And then there was the time, back in the '70s, when I had a blowout in the right front of my old GTO - at about 110 mph. No drama at all.

Ugh, I don't miss that commute. Manteca to Oakland back when 205 was two lanes. Chicken ****s who stayed in the left lane on the Altamont because they were skeered of the dropoff past the right shoulder. 238 parking lot. Sinkhole and pavement collapse across all eastbound lanes because of 100+ degree heat. (Not that I have it a lot better right now...)

/End threadjack

I guess I lost my own bet. My front flat was on a car without power steering, and I weighed under 130 lbs at the time. All my other car flats were rear tire incidents.

My front motorcycle flat happened on a curve, and I couldn't keep the bike on my side of the road. Fortunately, there was no oncoming traffic when it occurred.

Why would you run 65psi? Why would you even run sidewall max of 55psi? Now you see why it's foolish--- tires aren't cheap. Either you wear them unevenly with the high pressure or you damage them, and it ends up costing way more than you saved in gas.

The tire pressure didn't have much to do with the failure. It was the age. When I got my tires replaced, we noticed that they were made in 2002 :eek: and that they had some dry rot more serious than I thought.

I went with a matching pair of p215/75 with a surprising amount of tread on them for $30 each (I'm not going to ask the shop where they came from). Made in 2008. Much better. I put them on the front and left the big ones on the back. 2 fold benefits: maintain the taller final drive ratio, and lower the front about an inch. Yeah, I have a hot rod jeep! :D:turtle:

Furthermore, with the old tires on the back, if one should decide to blow out, I will have a rear tire blowout, not front.

Thecheese - be aware, you CANNOT use 4wd at all, on any surface with those mismatched tires.

Regarding rollovers, some SUVs are definitely less stable than others, although a lot of it comes down to drivers that think they're going to handle like sports cars. If people knew how to drive them, there would be far less accidents and rollovers involving them. Same reason why so many get stuck off the road in the snow. Drivers think they're invincible and drive way too fast.