Last week, I wrote a lengthy piece about the ins and outs of buying used snow tires and wheels, using my 2004 BMW X5 as an example. It ended with my purchase of an extremely well-priced set of factory alloys and Michelin X-Ice tires with 10/32-inch tread. The catch—well, not exactly a catch; more like something I needed to research and be certain about—was that the wheels were from a later model X5.
BMW uses body codes for its cars. My 2004 is a so-called E53, and the one the wheels and tires came off was a 2010 E70. Some hasty on-line research conducted in the minutes between seeing the almost-too-good-to-be-true ad and sending the message committing myself to drop everything and go see the wheels and tires revealed that the two models have a minor difference in offset (2mm further outboard, ET46 instead of ET48) and an important difference in center bore, with my E53 X5 having a 74.1mm bore and the later E70 cars having a smaller 72.5 bore.
As I wrote last week, most modern cars have hub-centric wheels, where the center bore of the wheel sits on a raised ridge in the middle of the hub. If the bore in the wheel is too small, it won’t fit at all. If it’s too large, there’s extra room that needs to be taken up with adapters called hub-centric rings. You’d think that tightening down the conically-shaped lug nuts or studs would be enough to correctly center the wheel, but experience has shown me that if you don’t use the hub-centric rings, you are in fact likely to have wheel vibration issues. A quick perusal of some of the X5 user forums revealed that, other than caliper clearance issues when you try to use wheels from the six-cylinder cars on V-8 cars, E70 X5 wheels work fine on E53s, provided that you use 74.1 to 72.5mm hub-centric rings.
So, after seeing the $200 set of wheels and tires with my own eyes, acting like Frye from Futurama and doing the “shut up and take my money” thing, loading them into the back of the X5, and driving home, the first thing I did was order the hub-centric rings. They’re generally available in either aluminum or plastic. I’ve used both, and each has its advantages. The aluminum ones are more aesthetically pleasing, but the plastic ones are actually more resilient and less likely to get dented or creased. This time I went with $11.99 aluminum rings from Amazon.
Part of the appeal of buying tires on wheels is that you’re saving $100–$140 by not having to pay for mounting and balancing. You are, however, assuming the tires are, in fact, balanced. The better condition they’re in, the better the odds that they’re reasonably well balanced, but give them a good look to be sure. Presumably, you’ve already inspected the tires to be certain there aren’t any sidewall rips, gouges, or bulges and verified that the wheels don’t have visible dents that are certain to cause balancing issues, but it bears checking again to be certain.
Once I’ve re-inspected the wheels and tires, the next thing I’ll do is check the pressure in each. Even if they’re pampered shoes that’ve been stored inside since last winter, they may have lost pressure. Each should be close to spec (usually the magic 32 PSI) and they should be within a few PSI of each other. Even an old beat-up set that’s been sitting under the back porch for years should still have some pressure; if one of them is obviously low or soft to the touch, you can assume it has a leak that must be repaired. You can try spraying in and around the valve stem with soapy water to see if that’s the source of the leak (watch for bubbles). Whatever the cause, there’s no sense in mounting the wheel on the car if the tire needs to be repaired.
Next, check the rotation direction on all four tires. Many tires these days have unidirectional tread. If so, there should be an arrow that is intended to point in the direction of rotation. This will dictate which wheels are supposed to go on the left versus the right. Look for it. You may find that one of the tires is mounted incorrectly.
In addition, I take a tread depth gauge and measure each tire to put the most equally-worn pairs together as front and rear. If you do find that a wheel has visible damage, put it on the rear, as it’s less likely to telegraph vibration into the steering. Note, however, that if the car has staggered-sized wheels and tires, they can each only go in one position. Stage the wheels around the car in their intended locations.
Next comes the actual installation. As winter approaches, this may not be a trivial thing, since—unless you have garage space—plummeting temperatures and snow accumulation may make it difficult or impossible to do it yourself. If you need to just pile everything into the back of the car and drive it all to a nearby shop and pay to have it done, there’s no shame in that. Presumably, you’ve already saved money by finding a well-priced used set, so don’t kill yourself mounting them on the car. We all have limits.
When mounting any set of wheels and tires on a car, you need a firm, level surface, a floor jack, a lug wrench or breaker bar, a torque wrench, and a set of jack stands. If you don’t have an impact wrench, you need to crack the lug nuts loose with the wheel still on the ground. One of the advantages of an impact wrench is that you can put each wheel in the air and zip the nuts right off.
About those jack stands… whether you swap one wheel at a time or do a pair by jacking up the car’s nose or rear, I cannot stress enough how important it is to take the proper safety precautions. While it’s tempting to just slip a floor jack under the lift point for each wheel, yank a wheel off and slap another one on, it isn’t a safe practice. You should always “double-jack” a car, meaning jack it up, set it down on jack stands, and then leave the floor jack in place. Trust me, things can go wrong. Flat areas of the driveway aren’t as flat as you thought. Asphalt is softer than you thought. Floor jacks slowly lose their sealing with age. Plus, the use of the hub-centric rings adds time to the process, and every second that a wheel of a car is in the air supported only by a floor jack is an opportunity for disaster.
There’s another component to the double-jacking argument, and that’s the weight of modern wheels and tires. Some folks use the rationalization that it’s OK to quickly swap a wheel on a car that’s supported only by a jack, so long as you don’t put any part of your body under the car. While I may be able to easily lift one of the 13-inch wheels for my BMW 2002s with my upper body and set it on the hub, my 61-year-old self can’t do that with the X5’s 18-inch wheels. I have to sit on my butt, roll the wheel onto my knees, and raise it into position that way. When I do this, there’s no pretending that my legs aren’t under part of the car. While it might not be life-ending if the car slid off the jack, I could spend the rest of my wheelchair-bound days ruing my impatience.
Just double-jack the damned car every time. Once you’re in the habit, you don’t even think about it.
With a corner of the car in the air, pull off the wheel. With any luck, it just drops off, but due to the corrosion that naturally occurs between the dissimilar metals of the steel hub and the alloy wheel, it’s common for wheels to be surprisingly stuck on hubs. Usually a few smacks on the inner sidewall of the tire with the breaker bar will free it. If it’s stuck pretty good, rotate the wheel and smack the inner sidewall at 90-degree increments to wiggle it off. (You see why you should always double-jack the car?) If it still won’t budge, try penetrating oil and heat, if necessary. The nuclear option is to put the lug nuts back on slightly less than finger-tight, take the car down off the jack, put the lug wrench in the car, drive it at about 15 mph, and slam on the brakes. The twisting force of the wheel relative to the hub can be very effective in breaking the corrosion. Be sure to immediately use the lug wrench to snug the lug nuts back down before you limp it back to the driveway.
When I have a wheel off, I mark the inside with a Sharpie (“right front” or wherever) so I can put it back in the same place at the end of the season. I realize that there are different schools of thought regarding tire rotation, but since many tires these days have unidirectional tread (see below), they can only go in two places, not four, and when you combine that with the practice of putting the straightest wheels on the front, I just put them back where I had them unless there’s good reason to do otherwise. As they say, your mileage may vary.
If you’re using hub-centric rings, it’s important that you clean any corrosion off both the hub lip and the wheel’s center bore so the rings fit correctly. I use a Scotch Brite wheel on a drill, but you can do it by hand if need be. Some hub and wheel combinations seem particularly prodigious in their generation of corrosion; for these I’ll apply a thin coating of anti-seize compound on the inside of the wheel bore. Carefully slide the ring onto the hub, being certain that it’s fully seated all the way around.
In addition to cleaning the hub lip, it’s a good idea to also give a Scotch Brite pass to the broad, flat part of the hub’s mating face, as anything that prevents the wheel from sitting flush against it is certain to cause vibration issues.
Whether you torque the wheels to spec with a torque wrench as you lower each one off the jack or do all four together, that’s up to you. Just make sure that you do it. I used to eschew use of a torque wrench in favor of a good stomp on the breaker bar until I found out that I was massively over-tightening the nuts. Then, for years, I relied on my impact wrench, having roughly calibrated a certain setting on the impact gun to the approximate correct torque for my BMW wheels. But a few years ago, while I was driving on recently swapped wheels, I heard the unmistakable sound of a loose wheel about to come off. Having lost a wheel 35 years ago, it’s astonishing how little time you have between “What’s that noise?” and disaster. I made it to the breakdown lane just in time. It turned out that my impact wrench was dying and no longer tightening things down with the torque I’d previously calibrated. So, I’m now a bit of a stickler for correct lug nut torque, doing one wheel at a time, and then checking all of them to be doubly certain I haven’t missed anything. It’s generally good practice to torque lug nuts sort of like a cylinder head—that is, tighten them in a cross or star pattern, first snugging them down, then tightening them to spec.
Next, test-drive the car. Take it on the highway and drive it at speed. You really don’t want to discover that the left front wheel has an unforgivable vibration at 70 mph just as you set off with your family on a 300-mile drive to your mother’s house for the holidays.
Lastly, there’s the question of where you store the wheels and tires you just took off. If you have one of those tire-specific storage shelves in your garage, great. I wish I had that kind of space, but I don’t. For the rest of us, indoors is better than outdoors, and upright is better than horizontal—that is, don’t stack them one on top of the other, as moisture between tires can shorten the lives of the sidewalls.
Onward through the snow!
Rob Siegel has been writing the column The Hack Mechanic™ for BMW CCA Roundel magazine for 33 years and is the author of five automotive books. His new book, Resurrecting Bertha: Buying back our wedding car after 26 years in storage, is available on Amazon, as are his other books, likeRan When Parked. You can order personally inscribed copies here.