Door panel calls for 235/70-15, Sears installed 235/75-15. Sears installed pair of 235/75-15 on front, 235/70-15 are already no the back. The tire size database is incorrect, I checked the size with GM using the VIN. Axle broke within 50 miles of highway driving.
Sears is claiming that the damage couldn’t be caused by differing tire sizes. Manager claims difference is only 5mm (70’s vs 75’s). I learned very quickly and recently what the tire size numbers refer to, I’m shocked that the Manager of the tire shop didn’t know.
The car has 113000 miles, the car is in excellent condition. It was owned by my MIL until she died and we gave it to our son to drive.
Could that damage have happened that quickly?
Thank you all so much.
Sorry, flustered and aggravated.
The damage I referred to was the front axle breaking.
What, exactly, broke? The tire size difference would not cause the front axle to break, but could cause the center differential to break. The manager is exactly wrong, 70 vs. 75 is not 5mm, those are the profile measurements in percent. He is ignorant about tires, an amazing (but not surprising) thing for a tire store manager. The diameter difference (according to the Tire Rack web site) is 25" vs. 25.9", or 0.9", much more than 5mm. And that’s comparing new tires. If the rear tires were slightly worn, the difference could be an inch or more (25.4mm) in diamter.
Tire size is critical on AWD vehicles. All four tires must match as closely as possible. Sears knows better, or at least they should. The responsibility is theirs, regardless of what the shop manager said.
70 and 75 are not measurements of height. They are percentages. The new tires have a sidewall height 75% of the tire’s 235mm width, or 176.25 mm. The rear tires have a sidewall height 70% of the width, or 164.5 mm. That’s 11.75mm difference, not 5mm, difference, and it gets worse when you measure circumference, which is what determines the speed at which the tires rotate as you drive.
The rear tires were rotating faster than the new front tires. The two ends of the vehicle were fighting each other. This is what caused the damage. I’m surprised you didn’t feel it as you drove.
And, yes, 50 miles is enough.
Look up tire circumference information on the tire manufacturers’ website. Compare the new tires to the old tires and see the difference.
It’s very unusual for a drive axle to break, but it may have been the weak link.
That manager is an IDIOT.
235/75-15 = (((235 * .75) / 25.4) * 2) + 15 = 28.87"
235/70-15 = (((235 * .70) / 25.4) * 2) + 15 = 27.95"
About an inche difference in height. This will make a HUGE difference in a AWD system.
Sue Sears. Installing two tires that are not the correct size for the vehicle is bad practice in the tire business. Did they get your approval for the different sized tires prior to installation?
Your car has full time AWD which means it is sensitive to the size of the tires on each wheel. When the tires don’t match they roll at a slightly different number of revolutions per mile. The difference in rate of rolling has to be compensated for somewhere in the AWD system. Very small differences are ok, but in this case the differences were too great. This causes a build up of pressure within the system that gets released at the weakest point. In your case something in the front axle or something that drives the front axle was the breaking point.
Get an estimate of the cost to repair the damage, get a lawyer, sue Sears if they refuse to cover the repair costs.
I agree with everything. Sears screwed up and the manager is an idiot.
He apparently does not even know how tire size is figured based on his comment about the 5 MM difference between a 70 and 75 series tire; which is utterly wrong.
Sears should pay for this one and push them until they do.
I agree with the others, make Sears cough up the total cost of the repair AND install the CORRECT sized tires.
HUH?! …and these are the same people who when you want to replace one tire on an AWD vehicle will only sell you all four tires because they’re aware of the small differences in diameter between a new and worn tire and the damage that that can cause.
How on earth can the salesman insist that two different size tires have a small enough difference in diameter that it shouldn’t have damaged your AWD??? They are absolutely responsible for the damage done to your vehicle caused by the installation of the wrong size tires!
Thank you all for your help and advice.
I just went to the shop where the car is on a lift. The Sears inspector came yesterday, he hasn’t finished his report, but he told me he doesn’t think the damage was caused by the different size tires.
Here’s the Laundry List of what broke:
Drive shaft broke at the front differential
Front Differential case broke
Drive shaft slammed into driver side exhaust crushing pipe rubbed a hole
Needs:
Complete Front Differential
Front Exhaust pipe with Sensor
Front Drive Shaft
Transmission checked internally
Transmission bracket
Neutral Safety Switch.
Could it have been anything else? My 19 YO son was driving, he said it felt ‘tight’ when he was driving, but thought it was just the new tires. Car started to make scratching noise and began to smell funny. He was on busy interstate, slowed down, got into right lane, car started smoking and then lost all power. He got to the side of the road and called me.
Could it have been anything else?
Of course it could have…BUT…the wrong size tire is the most likely cause…and it can cause all the problems…
Tell Sears you do NOT agree with them…and you want a independent Mechanic to inspect the vehicle. They just don’t want to be man enough to ADMIT they screwed up.
Oh yes, all of that is the result of the incorrect tires being installed.
The front and rear tires were rotating at different speeds, and the differential tore itself apart trying to make up for the difference. Your son felt something was “tight” and he was absolutely correct.
The Sears inspector is banking on your ignorance and hoping you don’t know anything about cars or tires. He, too, is either stupid or lying. Maybe both. Either way, his job is to hold down costs for Sears, not spend thousands repairing your vehicle.
You need to have an independent mechanic inspect the damage and give an impartial opinion. The Sears inspector works for Sears. You’re going to have a fight on your hands. I suggest hiring a lawyer. You may need one.
Now you have to ask yourself, do you want SEARS to repair the damage?
I know what my answer would be.
Totally disagree with Sears inspector. This damage is consistent with my earlier post regarding build up of pressure that has to be released somewhere. It seems that the differential went out and then as the parts locked up the axle got jammed and broke as well. From the collateral damage the whole thing literally blew up.
Nothing else could have caused this amount of damage as long as there was normal fluid in the differential. You need to start documenting. Write down careful notes, what exactly did the Sears salespeople say, the Sears inspectors comments, go to the place where the vehicle was disabled and take pictures. Particularly look for signs of fluids that spilled on the roadway to show there was fluid in the differential. Take more pictures of the damage with the car on the lift. Get all your past service records together to show the car was in good shape prior to Sears installing the tires. Be careful what you say to Sears reps other than you are going to sue for a resolution.
They are looking to snowball you and the more prepared you are the better you can fight this one and win.
It’s time to pull out the owner’smanual and its warning about using different sized tires and what any allowable tolerance is, and how to measure it (probably steel tape and measured circumference).
I know that Subaru has some very specific info in their owner’s manual, but I don’t know what GM states about this. Use this as leverage to argue that the tire center should have known about AWD and their tire issues, and instead acted in a way that caused near-immediate damage to a properly running car.
Wrong service procedures you should mention:
- Selling you two tires that do not match in brand, size, aspect ratio,or tread pattern with the other two
- Selling you these tires despite published manufacturer’s information warning against this.
- Selling you these tires without checking the actual circumference between old tires and the new tires, and comparing to GM guidance for AWD on the Bravada.
Point out that all of this information is readily available to properly equipped garages, and the Sears installer should have checked first, before doing the installation. Clearly your door panel sticker has the minimum information required (coupled with the fact of the AWD vehicle) to conclude that the two tires installed were absolutely wrong.
The manager is dead wrong on difference.
The height difference from rim to tread is actually (235)*((75-70)/100)=11.75 mm and you multiply the 11.75 by 2 since two sides.
It is great the damage happened so fast. Get a 2nd opinion from an independent mechanic or GM dealership and head to small claims court. You will win based on evidence and mileage was so close.
Don’t put much faith into anything a clueless Sears manager tells you or what an inspector says. Neither are mechanics; they’re salesmen and buck-passers and the latter’s job is stonewalling and snow-jobs.
I had a Subaru transaxle (blown up, total scrap iron) on the bench once due to a quicky lube screwup and their inspector wanted me to “patch it up”. Right. Weld the case back together, weld sheared ring gear teeth on, etc, etc. What an idiot.
There’s a huge difference in tire diameter between the ones on the front and the ones on the back. Odds are great that since the 70 series tires are getting a bit difficult to find (around here anyway) that Sears did not have the 70 series in stock and simply threw on what they had; which was the 75 series.
The tire sale took precedence over knowledge and common sense.
Maybe an anonymous, polite call to Sears inquiring if they have any 235/70s in stock might answer that question?
They owe you.
Frank Lloyd Wrong. They broke the axle and may have caused other damage as well by installing the wrong size tires. The damage should have happened that quickly and it did.
If the AWD system was damaged, I would agree that it was the result of the wrong size tyres, however the damage in this case sounds like something else. Of course the something else seems likely to also be Sear’s fault. I suspect something happened while they were working on the car and the transfer case ended up supporting the weight of the car and was damaged. I suppose that it could have have been due strictly due to the size difference of the tyres, but …
In any case, I believe Sears is the source of the problem.
Year,make,model,engine… I would like to look up the AWD specs for the vehicle but you don’t provide the information I need.
Car is a 1997 Olds Bravada, 4.3L V6
Door panel tire size is 235/70-15. Sears tire store databases listed the wrong size. Techs & Manager removed 235/70-15 from the front only and replaced them with 235/75-15.
Thank you.