[DarkArkAngel]

Hey everyone! I had a bad week as far as my tires are concerned.

As per usual, a heavy Utah winter has left our streets bombed out wastelands that are ready to claim unfortunate souls tires at a moments notice. Unfortunately for me, I was one of those souls.

While I was driving to work in a blizzard I hit probably the worst pothole I ever have, nearly 2 inches deep and 3-4 feet long. Almost felt like when I wrecked my car into a curb. Of course as soon as I hit it I knew that my tire was done, so pulled over while the car chimed at me about the newly airless tire.

Fortunately the pothole only seemed to claim my front passenger tire, and didn't cause any damage to the wheel or suspension. Even more fortunately, I was able to relatively quickly use the included spare and jack to replace the tire despite the blizzard.

The final result was I was able to make it to work that night after going to a nearby gas station to inflate the tire to it's recommended 60PSI. I made the claim on Tirerack that night (Monday) and new a new tire arrived on Wednesday. I also moved the spare tire from the front to the back because the handling characteristics with in front during this heavy weather were... unpleasant.

In my infinite wisdom, I decided I would be fine to wait until the next day to get my tire replaced. This was a bad idea.

This is likely my fault, as I should have avoided even driving slowly on the freeway to work. This time without a spare I had to get my car towed back home and the next morning brought my full sized wheel with the damaged tire to be mounted with the new tire at a shop and changed at home.

We now reach my conundrum. I'm aware that it is a requirement of AWD vehicles to have their tires within a certain tread spec of each other. I had wrongly assumed that the shop I had brought my tire to be mounted at was capable of shaving down tires. (I later learned that Tirerack will do this for you before you order the new tire, another point for my ignorance).

I had no other choice but the put the newly mounted tire back onto my car as the spare was pretty much destroyed. I am now extremely concerned as the difference between my old tire (at 6/32) and my new tire (at 10/32) is past the 3/32 of spec Ford allows. Now granted, my rear driver tire might actually be a little less worn than the fronts so perhaps on the rear axle they are within 3/32.

Regardless, this leaves me with a few options.

1. Keep driving the car as it is and hopefully the drivetrain won't explode before the new tire wears down or perhaps air down the new tire to keep it's circumference similar to the old ones.

2. I found a shop that does do tire shaving, but only at their warehouse which would require who knows how many days for my car to be wheel-less (as my spare still needs replacement).

3. Claim one or more of my other undamaged tires through Tirerack and just have them send me new ones to match. I am not sure Tirerack will be happy if I simultaneously claim 3 other tires tho.

What do you guys recommended I do? Also, can someone explain to me how an open differential can be damaged by differing wheel speeds? Isn't that the whole point of open diffs, to allow wheel speed variety for turning and such?

Sorry for the long write up, but usually I find details are important and help flesh out the story. Plus I this worsened my week considerably and writing about it makes me feel better.

 

[OX1]

Not going to matter at all front to rear First, your RWD part of drivetrain is continuously varying torque split anyway. What % of time
is RWD at it's max percentage and even then, is it then a direct connection, or coupled by a hydraulically variable clutch setup?
Second, I have run brand new 245 PS4S's on front and beat to crap one's on rear for thousands of miles and zero issue.

Now side to side, as you mentioned are open diff's, but you are still running the spider gears slowly, pretty much all the time
with tires different dia's, side to side. How much that affects things long term, hard to say. Short term should be no issue.
Maybe do an "extra" oil change on that diff if you leave it that way for months, but I would try to get tires the same, side to side.

 

[Engineer]

Not really my area but I agree with @OX1 (who knows a lot more about this, and a lot of other things as well, than I do). I don't think you're at great risk here. Now if it were me I'd just buy a whole new set of tires as soon as possible, but I wouldn't stress about it either if it took a while. Just plan to get another set when you can though, would be what I would do. But like @OX1 said I don't think you are at great risk especially if it's on the back, and even more especially with the open diff we have. That's kind of the point of open diff anyway, although in fairness it's not usually a sustained situation where you're driving long distances at high speeds relying on the diff to compensate. But still in my mind I'm having a hard time seeing how that could really cause a problem unless you just do something extreme. I'd just drive it normally (as opposed to how a lot of us drive these things) until I could a new set of tires all around, if it were me.

 

[maydk65]

I'm with @OX1. Get a new tire to mount across from you other new tire and you should be good.

 

[Skylinedan 1]

The system isn't that picky, not like say a true FWD system where you have almost zero slip between the front and rear. Those are gonna be the ones that don't like two different size tires front to rear, far as side to side go, the diffs will put up with it a lot better than the AWD system. Think about it this way, city driving will wear the spiders and shaft a lot more than a car that see's almost all highway driving. All those turns going from one street to another can be hell on the diffs if they're not serviced from time to time.

 

[Wojtas]

I'm sorry to hear that, you've been having some bad luck lately.
I decided to perform the shaman's dance to drive away evil spirits from you and your car

When I brought the car I had 3 identical tires and one different - strange. I would also buy 2 new tires in your case.
Good Luck Man!

 

[DarkArkAngel]

I'm sorry to hear that, you've been having some bad luck lately.
I decided to perform the shaman's dance to drive away evil spirits from you and your car

View attachment 30890

When I brought the car I had 3 identical tires and one different - strange. I would also buy 2 new tires in your case.
Good Luck Man!

Why thank you 😂 I quite appreciate it.

 

[Engineer]

I'm sorry to hear that, you've been having some bad luck lately.
I decided to perform the shaman's dance to drive away evil spirits from you and your car

View attachment 30890

When I brought the car I had 3 identical tires and one different - strange. I would also buy 2 new tires in your case.
Good Luck Man!

Funny thing is when I saw that picture, in my mind I thought "huh that's kind of similar to what a diff has to do...."

 

[bbf2530]

Hi gang. Just to add to the information already provided. The issue with too large a difference in overall tire diameter/circumference is not only a limited-slip differential issue.

The ABS, TCS, ASC, Dynamic Handling/Dynamic Handling w/Torque Vectoring etc. etc. all operate to one degree or another by using wheel speed sensors (and others), in order to calculate differences in tire rotation speeds between all four corners along with steering wheel angle, speed, throttle, braking etc. And in doing so, those systems can apply brake and/or cut back additional torque to any end of the vehicle (front or rear). And in some cases (i.e. w/Torque Vectoring), even to individual corners of the vehicle, in order to maintain braking and/or handling control.

Therefore, if the tires have a large enough tread depth difference, it can lead to a large enough variation in RPM/rotational speed that the system may incorrectly read it as a possible loss of traction, braking or steering control. Then, the systems may needlessly apply the ABS or torque cutbacks to that end or corner of the vehicle. Of course, this may/will lead to overuse, overheating, premature wear and possible eventual failure of the system. This is why it is necessary to keep the tire tread depth within certain guidelines.

What is the allowable tread depth differential in our AWD vehicles? As mentioned by others above, normally in the ~3/32" range. Can we get away with more than that? Yes/probably/maybe, since there is certainly a safety factor built into that calculation. However, then we need to perform some cost calculations in our own heads, concerning how much of a chance we want to take between another new tire or three, versus a hefty repair bill for damage to one of the above mentioned systems, premature brake wear, etc.
Not telling anyone what to do, since none of us can make those calculations and choices for others. I am only making some of the pros and cons known.

Hope this information helps and good luck.

 

[Brad'sffs]

I would recommend finding the identical used tire off ebay or whatever. You should be able to find one with the same tread amount. keep that new one in the garage until they all need replaced and only buy three. I've had success with this and it sure beats throwing out three half used tires early. Good luck

 

[OX1]

e between another new tire or three, versus a hefty repair bill for damage to one of the above mentioned systems premature brake wear, etc.
Not telling anyone what to do, since none of us can make those calculations and choices for others. I am only making some of the pros and cons known.

Hope this information helps and good luck.

Good points. I will say that most on this list have pre-mature brake wear from "reasons" that have nothing to do with the mechanics of the car, LOL!
(I remember on my Mazda6, I would get maybe* 10K miles before the rotors were warped).

 

[Inertia]

Sorry to hear about your bad luck, DarkArkAngel. I hope you end up finding an easy and not too costly solution so you're not worrying about your decision. As you say it is too bad you didn't know TireRack would shave tires. When I was running my Cobra in Time Trails and Open Track, Toyo RA1 was the spec rain tire, and we'd get them shaved to 5~6/32nds as full tread would be dangerous. They always did a good job of it.

 

[65dustin]

Those interstate potholes are insane. Sorry to hear about your run in with one.

Back in Indiana you’d see 6 or 7 cars on the side of I465 every morning and if you were paying attention to them instead of the road surface, you were joining them. Some of the holes looked like a meteor hit the night before. Glad your suspension and wheel is okay. I hear our stock wheels are getting tougher to find.

I don’t know much about issues when running different tires, but I can say that after running on the spare for a day back in Jan after getting a flat, and using the car to bring the punctured tire into a “non-accredited” tire shop, when they put my repaired tire back on, the car wouldn’t let me go over 15-20mph with the traction control on. Scared the crap out of me. All 4 same tires, all 38PSI. It took a few miles of driving for it to figure out there was nothing wrong and reprogram. No issues on the spare at all but as soon as it got a proper tire back on… yikes. So who knows.

Better luck in the future bro.

 

[DarkArkAngel]

Hey yall, another quick question. I have decided I am going to replace the other tire here soon and once it arrives I am curious as to what end of the car the newer tires should go on. My gut says front since that's where the majority of weight and power is. Any other ideas? Thanks.

 

[OX1]

Hey yall, another quick question. I have decided I am going to replace the other tire here soon and once it arrives I am curious as to what end of the car the newer tires should go on. My gut says front since that's where the majority of weight and power is. Any other ideas? Thanks.

The experts say the rear, as they claim putting them on the front might cause oversteer, which they claim is less safe for most drivers.
I call BS on this, as that is really only an issue if the car is starting to slide sideways (if not, just correct your steering, mid corner).

If it is raining and your car is on the verge of sliding sideways, SLOW DOWN. the limit on these cars is very high, even in the rain. In the dry,
you have to be practically driving like you are on a race track to get any kind of oversteer in these cars (heck I would love it if I could get a bit
more oversteer, these front heavy pigs massively understeer, at or "over" the limit).

Now what are the benefits of having newer tires on front.

1. Less chance of blow out in front, and who wouldn't rather be able to steer after a blowout?
2. Less chance of hydroplaning in front, which is much more of a risk/issue with me, than theoretical "oversteer".
3. Our cars are FWD based, so traction and weight is centered on front (front tires will wear more, typically).

 

[65dustin]

I got some good responses to the same question in this thread if you wanna take a look:

Tires: one axle or all four? What's the requirement...

Living in New Orleans we deal with potholes similar to the upper peninsula in MI. I've developed a bubble in a sidewall, and also have a different tire that I had to have patched because of a roofing nail after hurricane Ida. I'm currently running on Nexen CP671s in the stock 235 size with about...

www.fusionsportforums.com

 

[bbf2530]

Hey yall, another quick question. I have decided I am going to replace the other tire here soon and once it arrives I am curious as to what end of the car the newer tires should go on. My gut says front since that's where the majority of weight and power is. Any other ideas? Thanks.

Hi DAA. When replacing only two tires (and leaving two worn tires), all expert tire sites/resources (i.e Tire Rack, Discount Tire etc.etc.etc.), and all tire manufacturers clearly state to install the two new tires on the rear. That goes for FWD, RWD and AWD vehicles.

If you take a look online, it is easy to find what the experts state.

So...you can take the word of all of the tire experts, or not. 😎

Let us know how you make out and good luck. 🍻

 

[OX1]

I will just add this one thing. As I mentioned, the "experts" only concern seems to be hydroplaning (and handling concerns after that). In my experience, hydroplaning only happens significantly on back roads (50ish MPH) with uneven puddles in the roadway. This leads to severe yaw in the vehicle, since the tire force against the water is significantly different on either side (especially in the front, from initial impact).

At that point, which is most times initially going straight, which way is oversteer and which way is understeer (hint, trick question ). I'll take the higher percentage of chance to steer, ALL DAY LONG, over what ever concern the supposed experts have on minor yaw at highway speeds (typically WAY over the speed limit in the rain, which is 100% avoidable).

It is funny that the experts are concerned about oversteer/understeer from hydroplaning and which is easier by a novice to control/correct, yet they don't seemed to be concerned with ACTUAL steering at all, which is what you have to do with yaw either way, after the hydroplaning (or many times during). Just "reducing speed", without steering correction, means you will be off the road or in the other lane you did not want to be in.

I'll toss this one out there just to "annoy" the masses. The COVID experts swore is was from a bat too (and I could go on and on about supposed "experts").

Hi DAA. When replacing only two tires (and leaving two worn tires), all expert tire sites/resources (i.e Tire Rack, Discount Tire etc.etc.etc.), and all tire manufacturers clearly state to install the two new tires on the rear. That goes for FWD, RWD and AWD vehicles.

If you take a look online, it is easy to find what the experts state.

So...you can take the word of all of the tire experts, or not. 😎

Let us know how you make out and good luck. 🍻

 

[bbf2530]

I will just add this one thing. As I mentioned, the "experts" only concern seems to be hydroplaning (and handling concerns after that). In my experience, hydroplaning only happens significantly on back roads (50ish MPH) with uneven puddles in the roadway. This leads to severe yaw in the vehicle, since the tire force against the water is significantly different on either side (especially in the front, from initial impact).

At that point, which is most times initially going straight, which way is oversteer and which way is understeer (hint, trick question ). I'll take the higher percentage of chance to steer, ALL DAY LONG, over what ever concern the supposed experts have on minor yaw at highway speeds (typically WAY over the speed limit in the rain, which is 100% avoidable).

It is funny that the experts are concerned about oversteer/understeer from hydroplaning and which is easier by a novice to control/correct, yet they don't seemed to be concerned with ACTUAL steering at all, which is what you have to do with yaw either way, after the hydroplaning (or many times during). Just "reducing speed", without steering correction, means you will be off the road or in the other lane you did not want to be in.

I'll toss this one out there just to "annoy" the masses. The COVID experts swore is was from a bat too (and I could go on and on about supposed "experts").

Hi OX1. LOL...The short story is: Other members here can believe the word of all tire manufacturers and tire experts (see below), or they can believe your opinion. I am not asking other members to believe my opinion. I have presented well established facts.

The longer story is: LOLOLOL...So now you know better than the tire manufacturers and all expert tire sources? Come on.
And no, despite your erroneous statement, a minimum of research would disclose that hydroplaning is not the "experts" only "concern". In fact one of their multiple concerns is tire blowouts, which you expressed great concern (and mistaken beliefs/opinions) about. So let's not attempt to cherry pick information and make false statements. And don't express your opinion as facts.
This is a case where you either have not performed the p roper research, or you just want to stick to an opinion over fact, no matter what.

All one needs to do is Google "Place new tires on the front or rear" to get the answer: Place new tires on the front or rear - Google Search for all the answers.

And no offense, but comparing the still ongoing research as to the origins of Covid, to where new tires should be placed, is one heck of an attempt at deflection. Perhaps we should also accept the "opinions" of non-experts such as yourself for both Covid/disease research and tire placement? Nah...not a chance.

What this comes down to is you expressing an opinion and telling others to believe you instead of all other sources, with no factual or research backup. And me, who is not asking others to trust my opinion, but to trust the word of all expert tire sources, including the tire manufacturers themselves.And empirical information which has been well established for many years.

I am truly sorry if this reply seems a bit harsh. But it is sometimes quite ridiculous (and time wasting) to need to explain to others that they actually do not know more than automotive experts.
And opinions do not overrule proven facts (with backed up research). We are all entitled to our own opinions, but not our own facts. Or to put it another way...and possibly annoy the smaller "masses"...There are no "alternative facts". There are only facts.
Plus, in some cases, pushing an incorrect "opinion" can place other people in danger. And that is unacceptable.

So now...others interested in this discussion can read and believe many expert sources explaining where to install new tires, and why to install them there, and pay attention to the experts: Place new tires on the front or rear - Google Search
Or...they can believe unsubstantiated opinions. I know from past experience that trying to convince some people that their "opinion" is incorrect is an exercise in futility, no matter how much information contradicts that opinion and proves them wrong.

However, for their own safety and common sense (possibly), let's hope others make the correct choices. I am looking out for others, not my "opinion".

Good luck.

 

[Skylinedan 1]

Because if it's on Google, then it has to be true. LOL