One tire more worn

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I bought a Saab 9-3 the other day, and going through it I find that one tire is worn more than the others. Three are between 7/32 to 8/32 and one is 5/32. Should I change the 5/32 tire?
 
No not yet. Swap the tire that has only 5/32nds with the tire that is(or seems) least worn. See if they'll even out.
I have a couple of curiosity questions...

1) Being a used car, do you know how many miles are on the tires?
2) What brand/model/size tire is it?
3) Do you know if these tires were ever rotated?
 
Originally Posted By: rooflessVW
I wouldn't bother; just keep that tire on the rear and change them all when the time comes.


I agree with RVW....

What year and how many miles on your 'new' Saab? I've thought of getting one myself.....they seem to sell for reasonable prices....
 
If you change the 5/32nds tire, the new one will have more tread than the others by a similar margin.

Is your 9-3 FWD, or is it one of the few with AWD? If it's FWD, I agree with the suggestion to keep the worn tire on the rear axle.

What model are the tires?
 
While it seems logical to put the 5/32 tread tire on the rear its actually better to put it on the front on a FWD car. The extra weight on the front tires will assist in preventing hydroplaning whereas in the rear it is more likely with a shallow tread depth.
 
Originally Posted By: Char Baby
No not yet. Swap the tire that has only 5/32nds with the tire that is(or seems) least worn. See if they'll even out.
I have a couple of curiosity questions...

1) Being a used car, do you know how many miles are on the tires?
2) What brand/model/size tire is it?
3) Do you know if these tires were ever rotated?


I don't know how many miles are on the tires, but three are from 2014; the worn one is from 2013. They're Kumho Ecsta Platinums. I don't know if they have have been rotated. I rotated front to back as there was edge wear on the fronts.
 
Originally Posted By: pbm
Originally Posted By: rooflessVW
I wouldn't bother; just keep that tire on the rear and change them all when the time comes.


I agree with RVW....

What year and how many miles on your 'new' Saab? I've thought of getting one myself.....they seem to sell for reasonable prices....


I have three Saabs, actually. This one is a '99 9-3 with 78k miles on it; it's in surprisingly good shape. I think Saabs are a very good value right now. The only trick is finding a good one, as different models and years have different, but sometimes, significant, problems.
 
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Originally Posted By: 555
While it seems logical to put the 5/32 tread tire on the rear its actually better to put it on the front on a FWD car. The extra weight on the front tires will assist in preventing hydroplaning whereas in the rear it is more likely with a shallow tread depth.

The wrinkle in this case is that it's only one tire. On any axle that gets power, you always want the tires to be as equal in tread depth as possible.
 
That's a good point. The Saab does not have a limited slip differential so one must compare if the (IMO) negligible extra wear on the transaxle is worse than the possibility of undesired oversteer. Plus we have to compare other factors that affect tire diameter. Temperature(one side of car in sun), weight distribution from side to side and tire pressure(to name a few). These factors(and others) which can/do influence one another are always present, so I would guess 2/32 difference in tread depth is something the Saab drivetrain engineers took into account.
Another question is which side on the front would one put the 5/32 tread depth tire on? On the left is where most of the weight transfer occurs during a right turn. Perhaps it's better to mount it on the right where it's still under the weight of drivetrain but without the risk of abruptly losing traction as it would on the left. Most turns in a country where drivers must drive on the right are right turns. My 2 cents.
 
What are the date codes on the tires, is one older than the other three?

It's a used car, so who knows anything about the history. Original owner could have been bad at installing the tires after a seasonal tire switch, running the same tire several seasons on the front, while the others got rotated around. I see this quite often, and the tread depth will be all over the place.

Also, on a FWD car, the RT FR tire will see the most wear, noticeably more than the LT FR. Not exactly sure why, maybe because right hand turns in city situations are much tighter than left hand turns in general.
 
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The 5/32 tire is about a year older than the others. I'm going to try and get a used tire to match the others.
 
Originally Posted By: ET16
The 5/32 tire is about a year older than the others. I'm going to try and get a used tire to match the others.


There we go, mystery solved. Previous owner probably got a flat a one point and only replaced one tire, then when the other three got worn, only replaced three.

Maybe replace the axle pair and stop this from continuing?
 
Originally Posted By: mightymousetech
What are the date codes on the tires, is one older than the other three?

It's a used car, so who knows anything about the history. Original owner could have been bad at installing the tires after a seasonal tire switch, running the same tire several seasons on the front, while the others got rotated around. I see this quite often, and the tread depth will be all over the place.

Also, on a FWD car, the RT FR tire will see the most wear, noticeably more than the LT FR. Not exactly sure why, maybe because right hand turns in city situations are much tighter than left hand turns in general.


Perhaps Honda's have More Ackermann and this is why you see more wear on the right front, I don't know. Exit ramps and entrance ramps take their toll on that left front.
 
Originally Posted By: 555
Originally Posted By: mightymousetech
What are the date codes on the tires, is one older than the other three?

It's a used car, so who knows anything about the history. Original owner could have been bad at installing the tires after a seasonal tire switch, running the same tire several seasons on the front, while the others got rotated around. I see this quite often, and the tread depth will be all over the place.

Also, on a FWD car, the RT FR tire will see the most wear, noticeably more than the LT FR. Not exactly sure why, maybe because right hand turns in city situations are much tighter than left hand turns in general.


Perhaps Honda's have More Ackermann and this is why you see more wear on the right front, I don't know. Exit ramps and entrance ramps take their toll on that left front.


Not sure what it is. Pretty much every single car that is in for it's first tire rotation, right front has the most wear, left front is the second, right rear is the third, and left rear has almost none.
 
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