The agony of used wheels and tires

Part of the dynamic of owning a dozen cars (more than most normal people, but fewer than a bona fide collector) is that I relentlessly try and contain the maintenance costs of the fleet. This often results in my driving on worse rubber than I should. I know, I know—safety above all things. I certainly don’t go out of my way to do things I know to be unsafe, but like most people, I sometimes learn life’s lessons by getting slapped a few times.

Now, I’m not stupid. When I bought Louie, my 1972 BMW 2002tii, sight-unseen in Kentucky last year, I knew that it hadn’t run in a decade. I intended to resurrect it where it sat and pilot it home a thousand miles to Boston. The seller told me that the tires were dry-rotted, so I ordered four new tires without batting an eyelash, even though the tires that were on it had seen so little mileage that they still had the wear nubs on them. Of course, little 185/70R13 tires like that are cheap, maybe $200 for a set of four, as long as you can still find them in that size. But on modern cars, with taller and fatter rubber, the tire cost adds up—particularly across multiple cars. So I keep trying my hand at Craigslist, looking for used wheels and tires. It rarely works out.

Witness my daily driver, a 2003 BMW 530i Sport stick. I bought this car two years ago during the kind of frigid weather we’ve been experiencing lately. I looked at it almost on a lark. The ad described how the car wouldn’t start, that it made “that clicking sound” when the owner tried to jump it. I told him that it likely just needed a fresh battery installed—the frigid temperature and high resistance in the cables was likely preventing it from starting with a jump. He didn’t believe me. I drove there with a fully-charged battery, dropped it in, the car started right up, and for $1500 it was mine.

Unfortunately, the car wore a tragic set of Pep Boys aftermarket alloys and barely passable winter tires. I badly wanted the correct Style 42 wheels. So I tried to find a good used set of wheels and tires. After all, if you buy tires and have to pay to have them mounted, that’s usually a hundred bucks right there, so if you can buy a set of tires already mounted on a set of good-looking wheels for about the same as just the tires-only price, it seems like you’re coming out ahead.

You rarely do. Here’s why.

Bent wheels

Having now done this a number of times, I’m at the point where I think it’s realistic to assume that any set of wheels you buy will be bent unless proven otherwise. The increasing use of low-profile tires (where there’s less and less tire sidewall to absorb pothole shock) exacerbates the problem, but even older wheels that take 60- and 70-series tires are far from immune. Massive pothole damage is usually plainly visible, but in order to know with certainty whether or not the wheels are less obviously bent, you need to spin each wheel. You can mount them on a non-drive hub on the car (the front hubs on a rear-wheel drive car, and vice versa) and spin them by hand, looking at both the outer and inner rim surfaces for wobble, but you have to get the wheels rotating at a pretty good clip to really judge straightness.

The way that I check wheels for straightness is to jack up the rear of the car, set it on jack stands, mount two wheels at a time on the rear hubs axles, then start the car and put it in gear. If the car has a limited slip differential, it should spin both wheels, allowing you to look at them in pairs. Obviously, extreme care should be taken when doing this, and thus I can’t really recommend that you do it, but it lets you efficiently observe the inner and outer surfaces of both wheels and judge straightness.

So you see the problem. Doing this in the comfort of your own heated garage, perhaps even on a lift, is one thing. It’s quite another thing to do this in someone’s driveway when you’re responding to a Craigslist ad, especially during the winter when you’re looking for winter wheels and tires. And yet, if you don’t, the odds that you’ll wind up with wheels that are bent enough to have vibration issues are pretty high. I have, in fact, twice hauled along a floor jack and jack stands and spent an hour in cold weather spinning wheels in someone’s driveway. One time I bought the wheels, the other time I walked. So I suppose it was worth it. But it gets real old, real fast. In terms of time and wear and tear on one’s aging carcass, remind yourself there’s actually a cost in saving money.

Bad Rubber: Several things can go wrong when buying used tires. The most obvious is tire wear. People will say things in ads like “80% tread depth” or “used two seasons” or “like new,” but those are all imprecise terms, and many times I’ve driven an hour only to find that the tires were done. In contrast, a tread depth measurement is less objective. New tread depth varies substantially depending on the type of tire, but for a new passenger car performance or snow tire, it’s reasonable to assume that new tread depth is about 10/32 or 11/32 inches.

You can find all sorts of references online about using a Lincoln-head penny to estimate tread depth. For example, when used as a worn-out indicator, if a penny is put into the tread with Lincoln’s head pointing down, if the top of his head is exposed, the tread depth is 2/32” or less, meaning that the tire is legally worn out. However, the best thing to do is buy a real tread depth gauge. An easy-to-read all-metal American-made Milton tread depth gauge is about $7 on Amazon.

Of course, since it’s winter, you know that tread depth is absolutely crucial with winter tires. Most modern winter tires are constructed utilizing two rubber compounds, with soft rubber on the outside that resists freezing and adheres well to snow and ice, and a more traditional compound beneath it. When the soft rubber compound wears off, there might still be what looks like good tread depth, but because they’re now running on the hard rubber, the performance of the tires in snow and ice degrades substantially.

Tire Rack’s guidance is that winter tires should have at least 5/32 inches of tread to be effective. But my experience has been that if the winter tire tread is that thin, it can strand rear-wheel-drive BMWs on the slightest incline. When you consider that you need to pay a hundred bucks to mount and balance a set of tires, used winter tires with 5/32 inches of tread left on them simply aren’t worth buying, at least not to me. Bringing a tread depth gauge when you look at a set of used tires allows you to accurately measure tread depth on all four and walk away if the purchase makes no sense.

If the tread depth is acceptable, check for tire damage. Tires take a beating from curbs; a certain amount of scuffing or abrasions are normal wear and tear. The line between abrasions and nicks is a fine one, but any slice or gouge on the sidewalls should be a deal-breaker. Check the tread surface for tire plugs used to patch holes. If they’re there, they’re usually pretty obvious. Whether a tire plug is a deal-breaker is up to you. On a lightly driven car, if other things check out, I wouldn’t rule it out. But it does affect the value.

Next is tire age. You can tell the age because tires manufactured since 2000 have a four-digit date code at the end of tire identification number, with a two-digit week and a two-digit year. Note that the code may be on the inside sidewall of the tire. Acceptable tire age is a function of several factors (gently driven Sunday cruisers are one thing, track rats are quite another), but at a minimum, the date codes can help you to check the seller’s story. If the seller says, “I bought ’em last winter,” and the date code is from 2011, it doesn’t add up.

Regardless of the date stamp, tires can be dry-rotted from age and sun exposure. This is easiest to see on the sidewalls since there’s no tread there, but it can certainly be present in the tread as well. As you’ll read below, take any sidewall cracking very seriously, even for a Sunday cruiser.

Lastly, when buying used tires, you can’t tell if they have flat spots or out-of-round issues until you put them on the car and drive on them. And if you’ve already bought them and they do have issues, you have no recourse. This reassurance is part of what you pay for when you shell out serious coin for new tires from a reputable shop.

In the case of my 530i, the original Style 42 wheel is very in-demand, and people were asking a thousand bucks and more for nice-looking sets with recent rubber. I hated to pay nearly as much for wheels and tires as I’d paid for the car. So, instead, I found a set of badly-corroded wheels with marginal tires for $100 and planned to refinish the wheels myself. It turned out that all four of them were bent to some degree, two of them badly. It used to be that you could throw bent wheels on the back end of a car and barely notice their imperfections, but that seems to be less true on modern cars with more sophisticated suspensions.

So I bought another set of corroded Style 42s for a hundred bucks, spun all eight, and selected the straightest four. I marked them with a Sharpie using codes like “S” for straight, “B” for bent, “SB” for slightly bent, and “VSB” for very slightly bent. Out of the eight, I only marked one as straight. It, and one marked VSB, were tagged to go on the front. One VSB and one SB went on the back.

I selected the best two of the bunch and sourced two more used tires from Craigslist. When I took everything into a local tire shop to get them mounted and balanced, the shop called and told me that one of the tires had dry rot in the sidewalls. I went in, looked at it closely, thought they were overreacting, and asked them to mount and balance the tire anyway. A month later I had a blowout at speed on I-95, and when I realized it was that tire, I thought, OK, it’s real—no fair going into denial mode. I replaced it with a matching tire bought from bestusedtires.com, a site I probably use more than I should.

I am resolved that, when we get through this hell of a winter, I will buy a brand-new set of three-season tires for the 530i.

To review:

• You can’t really tell if used wheels are bent without spinning them, so as inconvenient as it may be, you have to do it. If you don’t, you’ll need to factor that in as risk.
• Check used tires for tread depth, age, and damage, and treat what you find seriously. Imagine yourself in a bad situation, and then decide if you still want to save money this way.
• If you’re buying winter tires, unless you just want basic rim protectors, you need more than the recommended 5/32-inch tread depth. Winter tire tread that skinny considerably less useful in snow and ice on rear-wheel-drive cars.

Having said all that, you’ll appreciate why I decided “no more used tires for this guy,” and bit the bullet and ordered a set of brand-new snow tires. Not an hour later, a friend contacted me and said that since he and his wife are planning on selling their house in the spring, he would gladly swap eight sets of wheels and tires in his basement for a set of two-season Bridgestone Blizzaks on aftermarket wheels, just to get them out of the house. What’s more, he has a heated garage with a lift and offered to hoist up the car and throw them on, right then and there. He sent me a photo of the tires, and the tread looked pretty beefy. I took him up on his offer and cancelled the order for the new tires.

Wouldn’t you?

When I arrived at his house, I found that he’d already selected the straightest two wheels for the front, and that the rear tires had between 9/32 and 11/32 inches of tread on them, with the fronts a little skinnier but entirely serviceable.

You aren’t likely to find the same on Craigslist. So don’t do anything stupid. Be careful economizing on wheels and tires. Even if you do have 12 cars. Because that already says quite a bit about your mental forbearance.

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Rob Siegel has been writing the column The Hack Mechanic™ for BMW CCA Roundel Magazine for 30 years. His new book, Ran When Parked: How I Road-Tripped a Decade-Dead BMW 2002tii a Thousand Miles Back Home, and How You Can, Too, is available here on Amazon. In addition, he is the author of Memoirs of a Hack Mechanic and The Hack Mechanic™ Guide to European Automotive Electrical Systems. Both are available from Bentley Publishers and Amazon. Or you can order personally inscribed copies through Rob’s website: www.robsiegel.com.