dcmodels

as stated, can only two tires (front or rear pair) be replaced, or must all four tires be replaced at once? I have a flat in one tire that cannot be repaired. So can I only buy two new tires, or must I replace all four?

My owner's manual indicates I need only replace two, although replacing FOUR is "recommended", but not stated as _necessary_.

I cannot find anything about this in the factory repair manual, although since there is no index, there might be something that I am overlooking.

Anyone? Thanks.

1islandparadise

One thing I can highly recommend is trying either the search function here on AZ or Google. With both combined you are pretty much guaranteed to find the answer!~

Personally this is what I would recommend. If one tire needs replaced then replace that one tire. With this being said I would of course check the tread of the other tires also. If they are dry rotting (small cracks in tires) or low on tread they I would replace. Its best to replace in sets....both front....both rears....and of course both front and rear sets. Hope this helps!~

princelybug

iTrader: (16)

In your case, replacing 2 should do you just fine.

phoward_15

I would just replace the two. They will obviously do an alignment as well but that's fine. I'm always cautious of replacing just one, especially if the make of the tire is not the same as the rest.

chipmunk

You can replace just one and have the tire shop run the tire down to the same diameter of your other tire.

PoLuRDX

For me, I would check the life of the other three tires first and decide from there. If still a lot of life in them, then just replace one.

dcmodels

Here in Salt Lake City, Utah I had a difficult time finding a place to do that, and certainly not at a reasonable price. Do you know of any large national chains that do this? Anyway ...

*********************
I originally asked the question: “When ONE tire has been damaged and cannot be repaired, should I replace TWO or FOUR tires?” I asked this question because the Acura requirements for tire replacement differ greatly from those of other car manufacturers of all-wheel drive vehicles. I am still wondering why this is the case.

Anyway, here is my answer to my own question, applicable to the 2009 Acura RDX only. If you own a different year or model, be sure you read your owner’s manual – and I would personally like to know if a different year RDX manual says something different from the 2009 manual (see below heading).

· If the tires are worn less than 2/32 inch, then shave and replace ONE new tire (of the exact same brand and model only).
· If the tires are worn more than 2/32 but less than 4/32 inch, replace TWO tires (of the exact same brand and model only), on either the front or rear axle, as a pair.
· If the tires are worn more than 4/32 inch, then replace all FOUR tires, with brand and model of your choice.
· Never replace only two tires with a different brand or same brand but different model, from the other two old tires. The diameter and rolling count-per-mile (revolutions) will differ.

My process of reaching a decision, was by considering the following. This information might be useful to others who are replacing a tire, in helping you reach your own decision.

THE ACURA RDX OWNER’S MANUAL SAYS:
Of course I can read (and did read) what the Acura Owner’s Manual says for the 2009 RDX on page 363: “It is best to replace all four tires at the same time. If that is not possible or necessary, replace the two front tires or two rear tires as a pair. Replacing just one tire can seriously affect your vehicle’s handling.”

Emphasis above was added by me.

THE TIRE RACK SAYS:
There is a very nice article on the TIRE RACK web site, discussing tire replacement for four wheel/ all wheel drive vehicles. The Tire Rack is an online web site that sells tires by mail order, one of the largest online sellers in the country. And they sell everything from the most basic tire to the most high-end model tires. I have never purchased anything from them:
http://tires.tirerack.com/search?p=R&srid=S11%2d5&lbc=tirerack&w=All%20Wheel %20Drive%20Tire%20Replacement&url=http%3a%2f%2fwww %2etirerack%2ecom%2ftires%2ftiretech%2ftechpage%2e jsp%3ftechid%3d18%26&rk=1&uid=793609450&sid=2&ts=c ustom&rsc=VU:vC2k4YBlilNiX&method=and&isort=score& view=list&cref=champ

Basically the Tire Rack article says: “Mixing tire brands, tread designs and tread depths may cause components in the vehicle's driveline to fail.” That means the transmission or differential.
Also, “Regardless of the vehicle manufacturer's recommendations, the least stressful application is when all four tires are the same tire brand, tread design and equivalent tread depth.”

OTHER AUTO MAKERS SAY:
Further, the Tire Rack article says: “Here are recommendations from some of the manufactures that the Tire Rack currently serves for matching the tires used on their four-wheel drive and all-wheel drive vehicles.”

Audi
As published in their vehicle owner's manual, "rolling radius of all 4 tires must remain the same" or within 4/32-inch of each other in remaining tread depth.
Porsche
Cayenne within 30% of the other tire on the same axle's remaining treadwear.
Subaru
Within 1/4-inch of tire circumference or about 2/32-inch of each other in remaining tread depth


SHAVING ONE NEW TIRE TO MATCH THE TREAD DEPTH OF THREE OLD ONES:
And finally: the Tire Rack suggests that it is financially advantageous to shave one new tire to the tread depth of the other three, if the other three tires are less than half worn. This allows replacing only one tire rather than four. Shaving is a process that car racers use commonly, to remove tread from a new tire to a required depth. Tire Rack provides this service, if you purchase a new tire from them. Then you must find a local tire dealer to mount and balance the tire for you.

I found a local place that does tire shaving, but decided that the difference in price between shaving a single new tire and purchasing two new tires was not great. Remember to take into account the loss of tire wear (and cost) of shaving a new tire.

THE LOCAL TIRE STORES SAY:
When I went to Costco to purchase tires, they refused to replace less than all four tires, their reasoning being that my vehicle (2009 RDX) is 4 wheel drive. I checked with a couple of other tire stores, and they also recommended replacing all four tires. This was probably because of the different manufacturer recommendations. So the tire dealer simply always chooses to recommend replacing four tires, rather than try to decide based on which car model you are driving.

ACURA CLIENT SERVICES SAYS:
I called the ACURA CLIENT SERVICES people at 1-800-382-2238, phone number in the RDX Owner’s Manual. The person who answered simply read to me the Owner’s Manual page as indicated above. But he offered no further information.

MY LOCAL ACURA DEALERS SAY:
I checked with my two local dealers (actually the only two in this state). The service writer in one dealership stated that they agreed with the RDX Owner’s Manual, and that replacing two tires is what she recommended. She also stated that the MDX (note different car model) Owner’s Manual recommends replacing all four tires when only one is damaged, but that she has observed that many MDX owners replace only two tires. I have not read the MDX manual, so do not know what it actually says (or recommends).

The service manager of the other dealership gave me a printed copy of a SERVICE NEWS ARTICLE from December 2007. He also did a search of his Acura database for any TSBs (technical service bulletin) or other information concerning this question of tire replacement, but found none.

The Service News article basically says when replacing two tires, always put the new tires on the rear. I would do this only if the old tires were more than 1/2 worn. Note that this article was published only shortly after the RDX was released as a new model. Read the article here:
https://acurazine.com/forums/showthread.php?t=771750


DECIDING HOW MUCH TREAD HAS BEEN WORN FROM A TIRE:
Well this is not really as simple as it sounds. You must first know how much tread a new tire has. I doubt that anyone is going to measure the tread depth of their tires when new – I certainly did not. Also, you must be careful to distinguish between total tread and wear tread depths. Suppose that a new tire has a total tread depth of 10/32nds of an inch. The wear tread depth is only 8/32 inch, because the tire must be replaced when only 2/32 of an inch remains.

The original factory Michelin Pilot HX MXM4s are on my vehicle, with remaining tread of 6/32 from the original 9.5/32 inch. That last is not a typo, as the Michelin web site states the original tread depth is 9.5 thirty seconds of an inch. And that is where you can find the original new tire tread depths. Search online for the original manufacturer of your specific tire and model. Tread depth and other useful information will be given, such as tire diameter and rotations per mile.

So for my specific tire, at 6/32 inch remaining total tread, the tire has worn off 3.5/32 inch of tread. This meets the Audi limit that all four tires must be within 4/32 inch of total tread depth, since my tires have worn less than that amount.

This amount of wear would NOT meet the SUBARU limit, requiring the replacement of all four tires (see section above under OTHER AUTO MAKERS SAY). My tires have worn more than the 2/32 inch differential allowed by Subaru.

Now, if I owned a Porsche Cayenne (I wish), and if the wear is less than 30% then only ONE tire need be replaced. The implication is that if this wear limit is exceeded then only two tires may be replaced (although this is not stated explicitly).

Anyway, in the case of my RDX, there is more than 30% wear on the tires. The original tread depth was 9.5/32, and the remaining tread is 6/32. So

(9.5 – 6.0) = 3.5 / 9.5 = 37% wear

HOW I DECIDED HOW MANY TIRES TO REPLACE:
The RDX Owner’s Manual states that only two tires (on the same axle) need to be replaced when one is damaged, without regard to tire wear (implied). Both my local dealers state that this is their policy when replacing customer tires. The Acura Client Service call line supports this policy.

I have decided to include wear limits in my tire replacement decision, as described below, in order to limit any potential stress to the drive train of the RDX. That is my own choice, although Acura makes no written comment concerning this topic.

My own personal decision is to replace only two tires when the wear is less than 4/32, based on the limits set by other manufacturers. If the wear were more than 4/32 inch I would replace all four tires. I make this decision in order to limit the stress on the RDX drive train.

Also, if the wear on my tires is more than 50% of allowed wear, then I would also replace all four tires. I make this decision as an economic tradeoff between cost and limiting stress on the RDX drive train. Here I refer to percentage of _allowed_ wear, not percentage of total tread depth. For this original equipment tire, this is basically 4/32 inch of wear from the total tread depth.

Tires must be replaced when the total tread depth remaining is 2/32 or less. So for a tire that is new with a total tread depth of 9.5/32, the amount of tread allowed for wear is only 7.5/32 inch. So the percentage of wear on my tires, of allowed wear is:

3.5 / 7.5 = 47%

or 53% remaining wear. The projected total mileage for this set of tires, based on the current mileage, would be 26K miles.

WHAT ABOUT THE TIRE PRESSURE SENDER aka VALVE STEM?
It has been standard practice for tire dealers to replace the tire valve stem when a new tire is mounted. I think that this is a very good idea. However, with a pressure sensor, as installed on all new cars, the valve stem is part of the pressure sensor. The valve stem cannot be replace without replacing the pressure sensor.

But only the rubber seal on the pressure sensor requires replacement, which is basically what is getting replaced when a rubber valve stem is replaced (the rubber seal). Tire dealers have kits which replace this rubber seal on the pressure sensor/ sender, as well as the plastic mount, and in some cases the metal washer.

I would encourage everyone to have this kit installed on the pressure sensor whenever a new tire is mounted. My tire dealer also recommends this kit any time the tire is dismounted, such as for a flat repair. I think this is good advice, since my dealer only charges $7.50 for the kit, including installation if the tire is dismounted.

ROAD HAZARD CONSIDERATIONS:
If you purchased Road Hazard insurance for the damaged tire, then the tire will be replaced without charge, which can affect your overall decision making. In my case, since the tire was original car equipment, there was no road hazard coverage.

TIRE CREDIT AND TRADE IN CONSIDERATIONS:
My tire dealer did give me some credit for the damaged tire through Michelin, even though I had no road hazard insurance. Note that no matter how many tire sets I have purchased at this dealer, or how many times I have been there, I have to ask if there is a possible tire credit in order to receive it. I do not know how the amount of credit is determined, nor have I ever tried to negotiate the amount. I just ask if there is a credit, and how much it might be, implying that the amount will determine if I purchase my tires there.

I have never asked for a credit for any other tire brand, so I do not know if this is a manufacturer specific thing or not. Anyway, this type of service is one reason that I have purchased probably 20 sets of tires over a 30 year period from this same dealer, and he knows it. Also note that I have never purchased road hazard insurance, although the dealer tries to get me to purchase it each time I buy tires.

Also, the tire manager gave me a trade in credit for the ‘good’ tire that I replaced. Remember, I replaced two tires, a damaged one and an undamaged one. This trade in credit I also had to ask for. This means that the dealer bought my ‘good’ used tire and will resell it as a used tire, on his dealer online web site. Again, I make no attempt to bargain on this credit amount, just ask what the dealer can do for me. This trade-in credit is only offered for an undamaged and non-flat-repaired tire.

So this tire dealer gave me the best price I could find, for two new tires of this particular Michelin tire, plus a damage credit for the damaged tire, plus a trade in credit for the undamaged tire. The two credits totaled about $100.

If you want this type of service, you will probably need to ask for it. This is money out of the tire dealer’s pocket, so he is not going to just offer it. When my wife goes to this dealer, she is never offered this service, unless she remembers to use my name. Also, you will probably need to ask to talk to the dealer owner or manager. And either state that you are a long-time customer, or plan to be one.

mason zonin

In my opinion I would say go to a used tire place and find a tire with similar tread to the other tires and about the same wear on it so instead of buying a new tire and having them wear it down you get one that's already the same for cheeper and they also mount and ballance it for you. So if only one tires your problem that's what I would do, no need to waist your money if the other tires are still good

mrgold35

I've used eBay twice to find used same sized tires with same amount of tread left as the originals. Once for my daughter's Mazda3 5dr hatchback and when I converted to a full size spare for my MDX. I wanted the spare with about 65%-75% tread to closely match my regular tires if I get a flat at anytime during the +50,000 miles tire treadlife. I put +20,000 miles per year on the MDX and I know I will not be close to home with a flat and don't want to have to drive too far on a donut. I think I spend around $70-$80 with shipping included for the replacement.

Tomtwtwtw

Not sure a 7 year old question still needed answering, but as long as we're here...with any full time AWD car, it's a good idea to keep the diameters of the tires as close together as possible. Some cars are more sensitive to differences than others, all depends on how the system is set up (Subaru comes to mind). But, if you do end up replacing only two, change up your rotation schedule to allow those tires to wear down quicker to match the existing set. Once your tread depth is about the same on all tires, go back to normal rotations.