How can I tell if my tires are completely worn out?

The tires on my XJ are worn out, no doubt about it. They have almost 75,000 miles on them. I'm going to be getting new wheels and tires soon, but I'm keeping the old ones as spares. The old ones need balancing, which I can have done for free provided they have more than 2/32nd's tread left.

How can I tell if they've got 2/32nd's tred left without a tread gauge? There are some small lugs in the tread that I think might be to tell you when they're worn to this level, is that the case? I can take a pic of it if no one knows what I'm talking about...

Get rid of the old ones, buy a 5th for a spare. Quit squirreling them away for a rainy day cause you will never use them and then have to get rid of them later on. Once they are worn down to the 'wear bars' they are shot.
It's called 'tough love' and I go thru it with alot of stuff, 'gee, maybe I'll need this some day', result is I needed a dumpster to start cleaning out my cellar and I will have to bring another one back to finish but at least now I can walk around and find stuff... I keep thinking of all those perfectly good 386 and 486's mainboards and processors I heaved, been 5 months now and I have not needed a single one :laugh3:

When I was stupid, poor, and in college (wait a minute - I'm still poor. No comments about "stupid!"), I ran a set down to the steel belts. You could see sparks when I went around curves. Ha! I thought it was cool :laugh3:

ZmOz said:

How can I tell if they've got 2/32nd's tred left without a tread gauge? There are some small lugs in the tread that I think might be to tell you when they're worn to this level, is that the case? I can take a pic of it if no one knows what I'm talking about...

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I agree with others - if you see the wear bars the tires are done. Tire companies have included wear bars for a long time so I doubt you have tires without wear bars. Count yourself lucky for getting 75k on a set of tires.

However to answer your question - the distance from the edge of a penny to the top of Lincoln's head is a good, and affordable, instrument for checking for minimum tread depth.

The "lugs" you see in the tread are the wear bars others speak of. These lugs are supposed to be set at 2/32", so when the tire tread is worn down to that level, they are "legally' shot. However, keep in mind that a tire's performance will usually degrade significantly as the tread gets close to the wear bars, particularly in adverse conditions. So, if you have significant rain or snow in your area, consider carefully the benefits of keeping worn tires. Shallow tread will not displace water/snow very effectively, which may leave your vehicle susceptible to hydroplane in these conditions.

The penny test mentioned by highhilleer makes a good depth gauge.

RichP said:

Get rid of the old ones, buy a 5th for a spare. Quit squirreling them away for a rainy day cause you will never use them and then have to get rid of them later on. Once they are worn down to the 'wear bars' they are shot.
It's called 'tough love' and I go thru it with alot of stuff, 'gee, maybe I'll need this some day', result is I needed a dumpster to start cleaning out my cellar and I will have to bring another one back to finish but at least now I can walk around and find stuff... I keep thinking of all those perfectly good 386 and 486's mainboards and processors I heaved, been 5 months now and I have not needed a single one :laugh3:

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That wasn't the question I asked. Where did I say they were worn down to the "wear bars"? The tread is currently about double the thickness of the wear bars. There's absolutely no reason to spend $200 on another wheel/tire when I'll have a set of 4 perfectly good ones left over. The tires happen to be the same size and wheels the same bolt pattern as the ones I my boat trailer, which also needs a spare, so I'll be using two of them as spares. I'd say the tires easily have ~2 thousand miles left...

ZmOz said:

That wasn't the question I asked. Where did I say they were worn down to the "wear bars"? The tread is currently about double the thickness of the wear bars. There's absolutely no reason to spend $200 on another wheel/tire when I'll have a set of 4 perfectly good ones left over. The tires happen to be the same size and wheels the same bolt pattern as the ones I my boat trailer, which also needs a spare, so I'll be using two of them as spares. I'd say the tires easily have ~2 thousand miles left...

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You asked how to tell if they are worn out. Several people answered.

As to where did you say they are down to the wear bars, you wrote:

How can I tell if they've got 2/32nd's tred left without a tread gauge? There are some small lugs in the tread that I think might be to tell you when they're worn to this level, is that the case?

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I read this to say that the tires are worn down to the wear indicators, and I assume other people understood it the same way. Even if you have a couple of 32nds above the wear bars, that's still not a lot of tread and doesn't make for a very useful spare. It's your decision, but people gave you good advice in response to your question and it appears that you didn't really want an answer that didn't agree with your pre-decision.

Eagle said:

You asked how to tell if they are worn out. Several people answered.

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And to those that answered the question, thank you. I wasn't looking for advice on whether or not I should use them as spares, otherwise that's what I would have asked.

Eagle said:

I read this to say that the tires are worn down to the wear indicators, and I assume other people understood it the same way. Even if you have a couple of 32nds above the wear bars, that's still not a lot of tread and doesn't make for a very useful spare.

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Just because I can SEE the wear bar? You can SEE it on a brand new tire. Any amount of tread on a full size spare is a hell of alot better than the stock donut. The jeep drives fine now with 4 of these worn out tires, I think I'll be fine using one of them for a few miles until I get the good tire fixed. It's not like I'm going to be putting on a bald spare and then driving 75mph through a snow storm. The purpose of a spare is only to get me home...and even then, 99% of the time I'd just have AAA tow me to the tire store.

I'm with you, if they are usable keep them as spares.
Why do you say they need balancing though? I wouldn't bother
balancing a spare even for free. If you actually have a vibration
issue then most likely they are worn unevenly rather than out
of balance, in which case I wouln't save them.

Tread depth gages are like $4 by the way..

gjxj said:

Why do you say they need balancing though?

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Because they start to wobble at around 55mph.