Few things are more frustrating than an unexpected flat tire. 😔

Just had a flat tire 185 miles away from home.. Donut held up pretty good..

Your reference to "as many right turns as left turns," occurred to me also. I would like to see an explanation from an engineer rather than a person selling tires.

First off, my apologies for not responding sooner. We are usually on top of responses but this one seems to have slipped by us. Its true I’m not an engineer and while I do “sell tires” the purpose of the video is to make the viewer aware of the reasons why shops and dealerships will call 4 tires on an AWD vehicle. Your skepticism about the sensitivity of AWD systems to tire wear, air pressure, and rotation practices is understandable, especially when considering the practical aspects of vehicle maintenance and the real-life usage of vehicles. However, the concerns about tire wear and its impact on AWD systems are indeed grounded in the mechanical and technical realities of how these systems operate. Let's delve into the specifics, particularly focusing on tire circumference, which you rightly pointed out as a crucial factor. Tire Circumference and AWD Systems AWD systems work by distributing power to all four wheels to optimize traction and handling. These systems rely on the assumption that all four wheels are turning at the same rate under normal driving conditions. Significant differences in tire circumference can disrupt this balance. 1. Tire Circumference and Differential Stress: The circumference of a tire directly affects how many rotations it makes over a given distance. If one tire has a significantly different circumference due to wear or incorrect size, it will rotate at a different rate than the others. This discrepancy forces the differentials and the AWD system's transfer case to work harder to compensate for the difference in rotation rates, leading to increased wear and potential failure over time. 2. Tolerance Levels: While specific tolerance levels can vary by manufacturer, a general rule is that the circumference of all tires should be within a 1/4 inch of each other. This translates to a tread depth difference of no more than 2/32 inch between the tires. Exceeding this difference can cause issues. 3. Real-Life Implications: In real-world terms, this means that even if tire pressure variations, rotation habits, and uneven wear (from making more turns in one direction than another) might seem minor, they can cumulatively lead to significant differences in tire circumference. This is why manufacturers and mechanics emphasize uniform tire maintenance. Addressing Your Points: - Air Pressure: Consistent air pressure in all tires is crucial because it affects tire circumference. A significantly underinflated tire will have a smaller circumference than a properly inflated one, disrupting the AWD system's balance. - Rotating Tires: Regular rotation helps ensure even wear across all tires, maintaining similar circumferences and preventing the AWD system from becoming stressed. - Spare Tire Use: The caution against using a compact spare (donut) in AWD vehicles is precisely because its circumference is usually vastly different from the regular tires, which can immediately put strain on the AWD system even over short distances. - Real-Life Experience: Many AWD vehicle owners and mechanics have observed issues ranging from unusual tire wear patterns to mechanical failures in differentials or transfer cases when tire maintenance advice was not followed. These observations underscore the importance of maintaining tire uniformity in AWD systems. The emphasis on tire uniformity for AWD vehicles is not about selling a "fragile drive system" but rather about ensuring the longevity and proper functioning of sophisticated mechanical systems designed to provide superior traction and handling. The discussion about tire circumference is indeed more technically relevant than tread depth alone, but tread depth is a more accessible measure for most drivers to understand and monitor, serving as a proxy for circumference in many discussions. While it may seem demanding, these maintenance practices are aimed at preserving the intricate balance within AWD systems, ensuring they operate as intended and avoid premature wear or failure. Thank you for watching and for your feedback. We appreciate both.

Different tread patterns while not ideal are not going to damage your AWD system. The tread DEPTH is what is important as stated in the video. 3 bald tires and 1 new tire is what you absolutely want to avoid.

@@UrbanAutomotive01 yes 3 bald tires and one new tire is not good I agree with that and I do agree that the tread depth as some effect but I don't think it damages the vehicle like people say it does all four of my tires were at different tread depths I would say as long as you're within an inch of each other you got nothing to worry about

Joe the symmetrical AWD on your Subaru is very durable but it does have its limitations. Think of it like going into a shoe store and only wanting the left shoe... there is a reason they sell them in pairs. If you did only get 1 new shoe... yes... you would be OK. After a while though you would start to "feel it" from walking funny. No different for the AWD system. The manufacturer knows the limitations and are the ones that set the recommended amounts. Keeping in mind we are talking about modern computer controlled AWD systems on modern vehicles and not 4WD systems on a 1/2 ton pick up truck from the 90's. A pair or set of tires on the Subaru are a LOT cheaper than replacing the components of its AWD system. 😉

@@UrbanAutomotive01 I agree with that statement but sometimes when you're growing up poor you just got to make due and at the time I had four tires that fit they were all different but they're all within an inch of each other with the tread and I honestly don't think it made one difference on that car and I was hard on that car that was what I was a little younger and I thought I was a race car driver LOL that's Subaru held up with everything I put it through on and off road so I am convinced that I just happened to get one of those vehicles that for some reason took the abused when I got rid of it it still ran like a champ I just happened to crash it and bent the right front truck assembly push the whole tire back and it was rubbing so I just got rid of it got a new vehicle would have been an easy fix but I was kind of tired of the vehicle anyways wanted something new

@@joejohnson9993 Yea from the research I've done, I've concluded this is just propaganda from people trying to sell you sh*t you don't need. Obviously take care of the vehicle you own, but seriously the whole "AWD" is so oversold, all the "safety for your family and whatnot", is BS, just want you to spend more money. Just drive slower and you'll be safer lmao. Can get away with 2WD and common sense. If you got a subaru you can get your new tires shaved down from TireRack if you really want to. But you'll be fine - think of all the non car people out there that have done dumb sh*t with their tires, have their differentials exploded? Prob not, but their head gasket's definitely have haha. What I've noticed is all the videos recommending 4 tire replacements after one flat are from shop businesses, hmm wonder why... Yes, get tire alignments and take care of your daily. But when shops are charging $80 for a simple air filter change(5 min job, $15 part), you gotta realize they're gonna bone you on many other services as well!

Most reputable tire shops will only install 2 new tires in the back, for safety especially on a wet surface. Even on FWD.

You are fine. Tread pattern differences affect handling and braking. While obviously not ideal the tread depth is the key to not affecting the AWD system of the vehicle.

@@UrbanAutomotive01 is that a yes or no

@@thedirtytowel3155 Tread depth is what can damage the drivetrain. If all the tires are within 2/32 of each other you are fine. Tread design (different brand tires) affect traction and handling but as long as the Tread depth is in the same parameters on all 4 tires you are OK and it will not do damage to the AWD system.

How does the car drive since? Did it mess around with the awd?

@@flacko001 car drives just fine, even with different brand of tires between the front and back. I was told as long as for each axle its the same brand, should be good. Who knows about long term tho. All 4 being the same is ideal though.

I'm baffled too,aren't all four wheels driven through differentials and isn't the function of a differential to isolate whatever is happening on 1 wheel from what is happening on another wheel?

just happened to me, bought a brand new awd car with obviously brand new tires. i’ve had it for about 3-4 months and one of my tires got punctured on the side wall. took it to discount tire and they measured all tread depths on all 3 other tires, considering they were still fairly new, i was good to go with getting the one new tire. if i was any lower on tread on the other 3, i would’ve had to get all 4 unfortunately.