Struts and Stuff

My (non-Lexus) mechanic (excellent, first-rate, the best) insists that my 2006 Lexus RX 400h with 25000 miles has bad struts. Lexus replaced the original Good Year Eagles after 20000 miles but only because (they said)the car had bad allignment. After 5000 miles on the new Michelins my mechanic again says premature wear from bad struts. Difficult for me to see the cupping or feel the chopping (but, hey, I’m no mechanic.) What do I tell Lexus? Should I wait until the wear is more apparent (at least to me?) Will Lexus accept my mechanic’s diagnosis? If I wait too long will that just kill another set of tires? What to do, what to do?

Lexus is not going to take anyone’s word other than the Lexus service dept. personnel.
Without knowing what the tread wear pattern looks like it’s impossible to tell if you have an alignment issue or bad strut issue. It’s rare, but possible for struts to go bad within 25k miles.

Question. Lexus replaced the tires due to a bad alignment. Was the alignment checked and corrected at that time?

If I make an assumption here that the edges of the front tires are feather-edging, etc. then this would probably point towards an alignment issue rather than a strut problem.

Hi ok4450,

Thanks for the response. When Lexus replaced the original tires (at 20000 miles) they checked and corrected the allignment with the understanding that we would monitor the tire wear every 5000 mile. Now its 25000 miles and my mechanic detects chopping which he attributes, as he did earlier, to bad struts. I’m about to bring the car back to Lexus for the 5000 mile check-up. If you are right about the feather-edging, can that be the result of bad struts, especially since the tires were alligned 5000 miles ago. Should the allignment be thrown off every 5000 miles? I’ve owned and driven many cars, including my wife’s 1999 RX 300, and have never had a tire problem of this kind. Can there be a deeper suspension issue as my independent mechanic says?

Since I assume you bought the vehicle new and it does not have any kind of shaky history behind it, I’ll have to defer to your mechanic.
A Lexus with only 25k miles, or less when this started, should not have a suspension problem.
If this is occurring on both front tires then it would be even stranger IMHO because the odds of 2 bad struts at the same time on a near new Lexus is not very good.

I had a heck of time finding a link with any tire wear pics. There’s a few here so you might look them over and see which one is closest to the pattern on your car.
Some of these are a little extreme and yours are probably not quite this bad.

Sometimes the wear pattern for bad struts and misalignment can appear similar, although a strut problem will usually cause the pattern to be a bit “coarser” if you want to call it that.

It would be interesting to know the alignment specs. Some alignment racks have the ability to print it all out and some don’t.
At this point I’ll just have to bow to your mechanic and the opinion of the Lexus dealer when you take the car in.

It’s time for that 5,000 mile talk again. At least they helped you last time.

What kind of roads do you drive on? Unless you drive over potholes on a regular bases, I find it hard to believe that your struts have worn out after a mere 25,000 miles. They should last much longer than that. The fact that your car should still be under warranty means that you should go to a few Lexus dealers to get more than one opinion, especially if you don’t believe what the first one tells you.

The fact that you had alignment problems at 20,000 miles indicates to me that your struts might have taken enough punishment to be worn out at 25,000 miles.

Hi Jeremy R Hoyt,

Thanks for the response. Nothing special about the roads I drive. Paved and normal as any. The RX 400h has a history of original Good Year tires prematurely wearing before 20,000 miles, which Lexus attributes to bad alignment. As you point out, even that is unusual especially if the roads are normal. Lexus replaced the Good Years with Michelins but here’s my concern – is the premature wear, which is beginning to show up on the Michelins after 5000 miles, the result of a suspension problem deeper than just poor alignment? Can the alignment be thrown off because of bad struts? Any idea along those lines would be most appreciated.

I would need to see the tires to get an idea, and even then I would not be sure by simply looking at the tires. Unusual wear can be caused by failure to rotate the tires sometimes, depending on your driving habits. How often do you have the tires rotated?

Describe the nature of the premature wear. Is a particular pattern forming or is the wear consistent over the entire tire? Could it just be that you are an aggressive driver and like to take corners fast? Don’t be afraid to admit it. After all, you don’t drive a Lexus the same way you drive an economy car.

Based on the fact that Lexus aligned the car, I am guessing the premature wear on the Goodyear tires was on the outside edges. This can be caused by bad alignment or by fast cornering. In fact, fast cornering can take the car out of alignment. Is the premature wear on the Michelins also on the outside edges? Be honest with me.

I’ve got a thought - if the tires are wearing on the outside, maybe check the tire pressure. Low pressure in the tires can wear out a set of tires very quickly. Check your owners manual for the recommended pressures, then check the tire pressures in all four tires with a good pressure gauge.

Of course, if the pressures are correct, then take the vehicle to your Lexus dealer to confirm the bad shock diagnosis, if your car is still under warranty.

Edit: I just noticed your above post stating the tires were wearing on the inside, which can also be a symptom of overinflation of the tires. Check the recommended pressures in your owners manual or on a placard attached most likely to the driver’s door, and ensure your tires meet those recommended ones.

Weak struts are not going to cause an alignment problem.

Hi Again,

Your response is much appreciated. Tires were rotated as prescribed. Interesting that you suggest the wear was on the outside. The wear was on the inside – close to the belts on the Good Years, beginning to show inside wear on the Michelins. I’ve driven my wife’s RX 300 since 1999 without any similar problems and I drive the 400h in the same way. Ti’s a puzzlement! (My abiding concern is that the alignment – which is the Lexus diagnosis – is being thrown out by soft suspension, which is inherent in the design. Could Lexus have compromised sound engineering for coushiness. Difficult to believe. Can a soft suspension throw off alignment?)

Wow, that really is a puzzle. So the alignment corrected a condition where the bottom of the tires were sticking out and causing premature wear on the inside edges. It sounds like you need a second opinion. Maybe a suspension expert will chime in on which parts to look at as a potential cause.

It does sound like a potential strut problem to me since struts bear weight. If the spring component of the struts were worn rather than the shock absorber-like component, I suppose it might make the car sag a little. Unlike shock absorbers, struts kind of combine the shocks and springs into a single unit to save space. So your original non-lexus mechanic might be right after all. If he is, an alignment is a part of the strut replacement process and it should all be covered under warranty and the best place to get the work done might be a Lexus dealer other than the one that worked on your car 5,000 miles age.

But the struts do allow for movement of the wheel up and down on an axis, right? If the springs were weak and the car sat lower than usual, wouldn’t that change the position and therefore the alignment of the wheels in relation to the rest of the car? Don’t they pivot on an axis as they move up and down? If no, please explain.

What if the car was overloaded? Would that change the angle of the wheels in relation to the rest of the car? Why would you not apply that same principle to weak springs on a set of struts?

Because a weak spring issue is not the same as a weak strut. A weak spring can have an affect on ride height, which could possibly have an affect on caster/camber, which would then have an affect on wheel toe. The odds of the OP having multiple weak springs on a near new Lexus is zero IMHO.

Overloading a car can have a slight affect on alignment but most of the weight of overloading rests on the rear wheels and normally overloading a car is not a day in and day out thing.

I was only asking about overloading the car as a demonstration of the principle I was describing. I don’t think that is the actual issue.

I agree that the odds of the OP needing new struts or suspension components after 25,000 miles is essentially zero, but I think this particular car might be the exception to the rule. What else, other than alignment or faulty suspension components, could cause uneven tire wear on the inside edge?

Thanks all for the terrific in-put on this puzzlement. Here’s an additional twist. When we bought the vehicle new, it came equipped with a class III towing hitch, the vehicle rated at towing a 3500 lb. trailer. During that first 20000 miles on the Good Years, we towed a small camper (dry weight 2385 lbs.) To insure proper load and handling the camper is equipped with a sway bar and equilizers. My mechanic dismisses the camper as causing the tire wear for two reasons: the camper is within Lexus towing guidelines. The added weight (within Lexus 350 lb.tongue weight, especially with the equalizers) adds no more than the equivalent weight of two adults in the back seat. Also we towed the same camper on my wife’s 1999 RX 300 with no tire or suspension problems. And the new Michelins (after 5000 miles) are beginning to show similar wear without any towing. Any thoughts about this?

Maybe we need to back up a few steps now that additional info is known.
Which tires are showing the wear problems - front, rear, or both?

Wear on the inside edges of the tires points to an alignment problem caused by too much negative camber or too much toe-out.

Both front and rear tires are showing wear problem.

When you say “inside” and “outside”, where exactly are you talking about? Overinflation leads to excessive wear down the center of the tire. Underinflation leads to excessive tire wear near the shoulders (outside and inside). Alignment problems can lead to excessive wear on the inside or outside of a given tire, but rarely both. Bad shocks (or struts) can lead to bouncy ride and cupping wear. Unless the OP is fond of slamming against curbs, smashing through potholes, or going airborne on speed bumps, the struts shouldn’t be worn out by now (unless they were defective builds). As the car is still under warranty, the dealer is obligated to take a serious look at the matter and discover what’s going wrong. If they won’t, go up the chain to the Lexus regional rep and higher.

When you say “equalizers,” do you mean a weight distributing hitch similar to this one? (Of course this one doesn’t have the way bar.) That would explain why the uneven wear is on all four tires.

You might consider taking the Lexus and the trailer to a truck stop to weigh the whole set-up. If you pull it onto the scale in the right position, you will be able to get separate numbers for each axle and the gross weight. Compare the gross weight to your vehicle’s GVWR (gross vehicle weight rating) to make sure you are not overloading the Lexus. With the whole set-up fully loaded, your gross weight might be more than you think.