Posted: Wed Oct 09, 2013 12:21 pm Post subject: Struts & Tire Wear
My 2003 Impala LS has developed a tire vibration problem that seems to only be prevalent at highway speeds (over 100 km/h / 62 mph). At lower speeds, I don't notice any unusual vibration. I had the local tire shop take it for a test ride a couple of days ago and they recommended new tires and a 4-wheel alignment. I installed a set of used Eagle RS-A tires at 203,830 km and my odometer now reads 236,123 km. I didn't notice any unusual tire wear at the last service (226,707 km - I've been following the OLM), which included a tire rotation and front tire balance.
The front tires now show cupping wear and the right rear tire shows caster wear (more wear on the inside). The tire inspection didn't suggest that I had any bad belts. A mechanic checked the front-end and did not find any excessive play in the suspension. The short ride that I took to the tire shop on the rough back roads here at 80+ km/h speeds gave me the impression that the ride was a bit wallowy but I don't usually drive at those speeds on those crappy back roads.
My take on the need for a wheel alignment is that the actual cause of the tire wear is worn struts and doing an alignment on worn parts is a bad investment.
Is there any chance that I could fix my tire wear problems with only an alignment?
If I replace the 4 struts with quick strut kits, will I need to do a 4-wheel alignment afterwards?
I don't think struts have anything to do with tire wear.
This is what I would do:
Rotate tires and see if the vibration changes location. This would lead me to a bad tire. Check tire pressure to make sure cupping isn't because of too much pressure. Check tie rods and wheel bearings by jacking the car up and checking for side to side and top to bottom wheel play. If none of that gets you anywhere I'd have an alignment done. I recommend a lifetime alignment. Firestone has it. Only the price of less than 3 alignments and it's lifetime for that car.
If that still doesn't fix it, buy new tires. You'll want to get it aligned with your free alignment after these are installed to make sure you get good wear out of new tires.
But if you want to replace struts, yes you need an alignment afterwards
2002 Impala- SSC, AGX, 18" charger R/t rims w/8mm spacers, Magnaflow cat, U-bend delete, flowmaster 80 series crossflow, z28 tips, HAI, debadged, 35% tint, smoked headlights, full sound system
Posted: Wed Oct 09, 2013 2:35 pm Post subject: Bent Rim
While trying to figure out the other .speed sensor issue I've been having with this car, I noticed that my right front rim is bent. The tire cupping only seems to be slightly more on the right front tire but I wouldn't have noticed it unless the shop pointed it out to me. The front tires definitely have over-inflation wear, with more of this wear on the RF tire.
I've been try to keep the tires inflated at the 30 psi recommended on my tire placard but I noticed that my previous tires had significant shoulder wear before I replaced them with the RS-As. The shop that mounted them inflated them to 36 psi and I've kept them there ever since.
I had a closer look at the back tires just now and only the RR tire has the camber wear. The LR tire appears to be wearing properly.
Unfortunately, there isn't a Firestone shop anywhere nearby unless i go over the river to Buffalo, NY
Part of your problem was starting with used RSAs... they are a terrible tire.
They were police car take-offs that I got for $35/tire installed. As far as used tires go, they didn't seem to be too bad of deal at the time.
Also, bad struts can absolutely cause issues with abnormal tire wear.
The guide recommended by IffyG suggests that bad struts would cause cupping over the entire face of the tire. It also suggests that cupping could have been due to out of balance and I found a bent rim on the tire with the more noticeable shoulder cupping.
One sign of worn struts is a bouncy ride which I don't notice on good main roads. However, having just did a jounce test, it takes more that 1.5 rebounds for the back end to settle. The front is stiffer and seems to settle within 1.5 rebounds.
So a strut or shock consists of a damper and a spring. The car hits a bump, the spring and shock go into jounce. Then, the suspension will go into rebound. The spring wants to fire the tire back to the road much like a gun, the shock or damper part of the strut controls the rebound portion back to the road. If left uncontrolled, as in a worn out strut or shock, the tire can become cupped, flat spotted ect.
I can't tell you why, but I suspect is something to do with an inability of the strut to properly dampen the suspension causing all sorts of extra motion while the well is rolling.
in addition to that, worn struts can cause an overload on the front tires mimicking low tire pressure (wear on inside and outside) and when coupled with an alignment that is out can often affect wear on one side or the other of the tire. as far as the rear tires go, the wear is often more cupped because of bouncing. Worn struts also allow more body roll creating more tire wear
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