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.