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2002 olds bravada
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I own a 2002 Oldsmobile Bravada AWD (SmarTrack). Unfortunately I can not find a good forum for these vehicles (succeeded by the Buick Rainier) so I am posting on this forum. If anyone can suggest any other forums that I can post on that would be great too please.

Two weeks ago I had a flat tire on my front axle. I took the Bravada to the tire shop and they installed a new tire. I know that an AWD vehicle needs to have all 4 tires matching, including tread wear, but I am wondering how much tolerance is acceptable between tires.

For those of you who don't know, the Bravada (and Rainier) only have AWD. There is no switch to turn it off like they TrailBlazer and Envoy. It is a different transfer case and it is always engaged, 100% of the time.

NOTE: I will only install the exact same tires. When I mention a difference in tire size, I am only referring to tread wear on the tire.

I am also wondering if the AWD system is more tolerant when done in pairs on the axle. I have read that AWD systems are more tolerant this way. Is this true? When there are different tire diameters on the same axle, is that more likely to cause issues? The rear axle has a Locking Differential, so I would think that matching tire diameters are more important on that axle.

My next question is a bit more involved. The Tire Shop installed the wrong tire size. All my tires are 235/65R17 and they installed a 225/65R17. The difference would be a 1/2 inch if the tires were all brand new. The tire wear on my old tires (larger specs) brings the tire a bit closer to the same diameter, but the shop really messed up! It's still out by at least 3/8 inch!

Fortunately I caught the issue of the wrong tire specification after about 500km. The vehicles started getting drag (AWD engaging) at about 350km and I drove it about 150km with the transfer case engaged. That 150km was at 100km/hr for 3x50 km trips (ughhh!). I figured out how to disengage the transfer case by removing my ATC(electonic transfer case) and 4x4 fuse and this disengaged the AWD. I have continued to drive without further incident, although I am aware the varying diameters it still puts stress on the front differential.

Does anyone think that I would have caused a lot of damage/wear to my transfer case? Or do you think this would have been minimal?

I have not talked with the tire shop yet, because I want to go in prepared. I was extremely irate when I found their mistake. The shop is Kal-Tire (a large franchise), so I expect a lot more out of them than this idiocy. I measured the wear on all of my tires to calculate the exact size difference, so I can tell them exactly how much the difference is.

I have not tested the AWD system since this incident, because I am taking the vehicle back to the shop on Saturday. I will get a new tire with the correct specifications. I will most likely get a second new tire (pending opinion/recommendation) to match and install them on the rear axle.

After installing the correct tire, I will test the AWD system. I know that the Oldsmobile Bravada Transfer Case is not meant to be locked in for extended periods (even on loose surfaces), so I am a bit worried about the wear on my vehicle. It is my understanding that the transfer case has some kind of clutch pads that grab intermittently during slippage. Can anyone clarify how bad this is? Is it easy to rebuild the transfer case? Is it just replacing the clutch pads? Does it cost a lot to rebuild? Does anyone know the make/model number of the transfer case?

I'm not sure how much liability, etc. the shop would be resposible for, since I caught this fairly early. I hope there is nothing seriously wrong, but it will probably be almost impossible to prove wear and tear. Does anyone think there is anything that I can nail them for?

At a minimum, they need to replace the tire for free. I'm thinking that I will probably need to get a matching tire for the axle. I am hoping they will give me a deal on that, If not I will purchase it elsewhere.

Thank you to anyone who reads all of this. If you have any answers, suggestions, and/or recommendations, I would greatly appreciate them. I bought this vehicle two months ago, so I am learning as much as I can about it. Unfortunately it's a bit rare, so finding a dedicated forum is not so easy. The vehicle is mechanically the same as the TrailBlazer and Envoy in almost every respect, except for the AWD system.

Thanks Again!
 

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2002 chevy trailblazer_ls
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Not being a lawyer you are pretty much on your own with some of that!

I would press the tire shop for damages but since you didn't drive very far before catching their mistake, they won't pay much and will mostly be for tire wear on the other tires and even then it is doubtful they will be willing.

Shoot for a new tire and as for damages to the hardware, problaby not much since you caught it before things started smoking.

Good luck!
 

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2002 olds bravada
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To be honest, I pretty much stopped reading your post when I read the tire size discrepancy. 235/65R17 and 225/65R17 tires are the same size, as in height. Where they differ is in width, one is 235mm wide while the other is 225mm wide. Both sizes are in fact 17 inches tall (diameter). If the 65 was not a match, the tires would still be the same height, but the height of the sidewall would differ. The 65 is a ratio of width to sidewall height, so the sidewall height on a 235 wide tire is 65% of the width. Low profile tires that have minimal side walls might be something like 235/30R17 whereas the sidewall is only 30% the width of the tire. A bit confusing, but it's not rocket science.
And just another bit of information - the Bravada is All Wheel Drive; all 4 wheels are engaged ALL THE TIME. That is why gas mileage is lower than similar Trailblazers that can engage and dis-engage the 4WD.
 

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2005 chevy trailblazer_ls
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To be honest, I pretty much stopped reading your post when I read the tire size discrepancy. 235/65R17 and 225/65R17 tires are the same size, as in height. Where they differ is in width, one is 235mm wide while the other is 225mm wide. Both sizes are in fact 17 inches tall (diameter). If the 65 was not a match, the tires would still be the same height, but the height of the sidewall would differ. The 65 is a ratio of width to sidewall height, so the sidewall height on a 235 wide tire is 65% of the width. Low profile tires that have minimal side walls might be something like 235/30R17 whereas the sidewall is only 30% the width of the tire. A bit confusing, but it's not rocket science.
And just another bit of information - the Bravada is All Wheel Drive; all 4 wheels are engaged ALL THE TIME. That is why gas mileage is lower than similar Trailblazers that can engage and dis-engage the 4WD.
You should read more. You have the bits and pieces right, but not the total.

Both sizes are in fact 17 inches tall (diameter).
No, both sizes fit on a 17" diameter rim.

The 65 is a ratio of width to sidewall height, so the sidewall height on a 235 wide tire is 65% of the width.
and the sidewall height on the 245 width tire will be more (as in 65% of 245mm).

Bottom line - with taller sidewalls on the same 17" rim, the 245s will be larger diameter wheels.

If you're not a rocket scientist, tire size calculators are available on many tire vendor websites.
 
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