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Discussion Starter #1
My wife went to leave to work just now, calls me a half mile down the road and says the TPMS light is on and she can hear hissing from the right rear tire and found a bolt stuck in it.

I'm hopeful it can be plugged, but in the event is cannot, is it ok to replace only 1 tire, with it being AWD?

The tires on it while not brand new, are a set of Michelin with likely another 15k of driving still on them. I'd hate to have to ditch them but also don't want to screw up the AWD with the slight difference in tire diameter.

Thanks.
 

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The best bet is to replace all 4. I hear TireRack will sell one and they can tell you how to measure the other tires and you provide the info...they will shave the tread to match the wear of the remaining 3. I don't know of anyone that has done this though.
 

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I can see replacing two, either the front 2 or the rear two, to keep them matched, especially if the same tire cannot be sourced, but all four???
 

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Discussion Starter #4
I did some research and even just on this site, came up with results for replacing 1, 2 or 4. Just going to hope this can be repaired, could not be a worse time to have to replace them.
 

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Every couple of months Sam's club has a special sale - the last one was $140 off a set of four BFGs ($80 rebate and free installation - normally $60 for 4). That is the main reason to buy four- to get the max rebate (I have bought two for one car and two for another before, I usually just bring the wheels to be mounted. They charge $5 extra to install a new TPMS if you bring the sensors in). I do not know which Michelins you have, some are great even half worn and some (Pilots) are not very good except for track day.

Now everyone has a different opinion but I always research tires on tire rack and do not consider any street tire with a UTQG less than 400 or rain traction les than9.0/excellent. For AWD I would buy all four the same size, either 235x55R18 or 235x60R17 (1/2" stagger on the wheels makes no difference).

To June 2nd they are also having a $20 off AGMs sale and have H6/grp 48 AGMs.

ps I do not compromise on tires. Have excellent street tires and for track/autocross I have a second set of wheels and tires good only for dry surfaces.
 

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Discussion Starter #6
I do not know which Michelins you have, some are great even half worn and some (Pilots) are not very good except for track day.
The ones I have on there now are Pilot Sport A/S 3+ nice tires that I'd hate to lose, never had a bad set of Michelins. 245/45/19s, another reason I'm hopeful this can be fixed, 19s are not cheap for a decent set (and I don't want cheap tires, especially on the family vehicle)
 

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The ones I have on there now are Pilot Sport A/S 3+ nice tires that I'd hate to lose, never had a bad set of Michelins. 245/45/19s, another reason I'm hopeful this can be fixed, 19s are not cheap for a decent set (and I don't want cheap tires, especially on the family vehicle)

This is where those larger wheel diameters starting showing their ugly truth, lower real tread life and exorbitant replacement cost compared to a 17" or even an 18" tire.
 

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With AWD you MUST replace all 4 at the same time or you will cause extra wear on the transfer case and if there is enough of a difference in circumference you will cause premature system failure. It can recognize when the spare tire is on and will disengage the AWD but otherwise, depending on the difference in tire size you are asking for trouble. You have to keep the tires near the same circumference thus the importance of rotation on an AWD vehicle.

Since a RWD vehicle does not have a transfer case you CAN change out 2 tires at a time but you need to keep the tires of the same age on the same end of the car. Front or back. To prevent side to side issues which can wear out the rear differential prematurely or cause your car to pull to one side or the other.

Rodney
 

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Discussion Starter #11
Thankfully it was able to be patched, checked the pressure again just now and it's good. Will check again tomorrow and keep an eye on it for the next few days.

That 140ft/lb torque for the wheel lugs was higher than I expected!!!

Also, does anyone else manual say check page 12-2 for wheel torque specs, but the specs are not there? Checked both my paper manual and the online copy at Cadillac owners.
 

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Best possible outcome. :) That 140 ft/lbs is very high indeed. Recommended torque values for 14mm wheel nuts range from 85-140 ft/lbs so Cadillac is at the extreme end. I do 125 ft/lbs.
 

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OH no, not the wheel lug torque issue again. I was tarred as a heretic for saying 140psi is higher than needed and probably to solve another problem such a brake rattle in a -V.

I actually cracked some cheap lug nuts torqueing to 140 psi (now have Gorillas that are stronger). It is interesting that for 2014 it was backed down to a more reasonable 110 lb-ft.

page 12-3 of my '11 coupe OM says "Wheel Nut Torque 190 n-m 140 lb ft"
 

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Discussion Starter #15
Dunno how I missed it while looking in my manual yesterday, I even flipped the page a couple times looking, but mine does also say 140 lb ft......... 2012 wagon.
 

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OH no, not the wheel lug torque issue again. I was tarred as a heretic for saying 140psi is higher than needed and probably to solve another problem such a brake rattle in a -V.

I actually cracked some cheap lug nuts torqueing to 140 psi (now have Gorillas that are stronger). It is interesting that for 2014 it was backed down to a more reasonable 110 lb-ft.

page 12-3 of my '11 coupe OM says "Wheel Nut Torque 190 n-m 140 lb ft"
The Cadillac mechanic told me it was 140 ft/lb also. They won't have to worry about me changing a tire on my own!!! lol
 

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Discussion Starter #17
They won't have to worry about me changing a tire on my own!!! lol
Seriously!! I am glad I was able to get our wagon home to remove the wheel, would have sucked trying to break those loose at the side of the road with the tire iron in the trunk.
 

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Again with the AWD tire replacement, with lots of unsubstantiated claims and warnings of impending disaster.
The engineers who design the drive line components KNOW that the axle sets will be operated with one bald tire and one brand new tire for at least normal operating conditions.
Also, a car (caution unsubstantiated claim ahead) spends 60% of travel turning, to some degree. So if you figure out how much wear and heat in the carrier sections spent on a corner, then add 200% safety factor to in, that is likely the design you have.
Same with the transfer case gearing.
We're not talking about Yugos here, these are all high end vehicles here. If this was a real risk to your vehicle, there would be FACTS published, on just what the actual limiting velocity difference was designed into it. It should be enough, with a safety factor, to allow any combination of bald and full tread on any of the 4 wheels, assuming otherwise IDENTICAL tire design & dimensions.
What is the velocity difference when running one of those tires at 26 psig and the remaining ones at 36 psig?
We know that will ruin a tire fast, but DESTROY the drive line? I think not.
I'm sure there have been anecdotal failures of driveline components when one tire was recently changed, but I suspect there were plenty of contributing factors that were overlooked, lubrication, extreme high temperatures, anything to assign the blame to the consumer if needed.
So, until I see actual figures published by the manufacturer, unloaded vs rolling diameter, not vague warnings designed to prevent someone from putting different aspect ratio tires on the same axle, or front to back on AWD vehicles, I say that people who have their new tires shaved are throwing money down the sewer.
Unless, perhaps, they are running at the limits of the vehicle, 120mph straight line driving in desert heat for days at a time. For that, even without the facts, I'd probably grind my brand new tire, even without the actual design parameters.
The cars we drive have to be reliable, no manufacturer is going to risk their market share by putting unreliable designs on the market, at least for very long.
Show us the FACTS!
 

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Well back in the Autocross daze we did used to shave tires for divisionals or nationals but not for local events (actually the Goodyear people provides pre-shaved tires to the fast people). When I was really serious the Sunbird used to go through a pair of tires and a wheel every weekend (SCCA F/S).

Since my main concern for a street car is our periodic deluges, I look for a tire that is excellent (9.0 or better) in the wet. The tires on the Judge are 235/60 front and 255/70 rear but it is more of a show(off) car.
 
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