Tire Size and AWD [Merged 5-7] diameter radius rolling different sizes size

[King Salami]

Gurus - I've got an 92 TSi AWD that I recently had to replace a tire on. All other tires are about 20% worn. Will the difference in tire diameters (due to wear; tire brand & size for the new tire is the same) cause any harm to my transfer case/AWD system?
I know wheel/tire size differences are very important on an AWD, but would 20% wear on 3 tires vs. 1 new make a difference? Since I rotated my tires, I'm experiencing an odd low-pitched "hum" or "grumble", especially when downshifting or raising off the throttle.
I've asked the guys at Discount Tire and my local Audi dealer, but they didn't seem too concerned.

 

[Defiant]

Aw, jesus christ, pop for a new set of Sumitomos. Or get out of DSMs. You can't afford them.

My effing god.

 

[Justfat]

Dont get used tires for an AWD car. even a 1/4 of an inch difference in tire tred will fry your transfer case in a few thousand miles. so spend the extra money now to avoid major problems later.

 

[boostedinaz]

That is what my heart is tellin me but the wallet is skeptical...

Ask you wallet what it likes more,some brand new regular everyday tires for about 350.00 or a new tranny and T case for a bit over 2000.00. I have a feeling it will agree with your heart alot more then you think.

Aw, jesus christ, pop for a new set of Sumitomos. Or get out of DSMs. You can't afford them.

My effing god.

Exactly.

 

[HighPsi92GST]

How much are you going to be paying for these used tires? I got a brand new set of Falken FK-451 225/50ZR16 to replace my old ones and paid 350 shipped to my door.

On a side note, be very careful buying used tires. I have a set of Continental 205-55-r16s and a set of (sorry forget the brand right now) 205-55-r16s. When you set them side by side, the one set is taller then the other. Not to mention the other set is quite a bit wider.

 

[nwgtr]

1992 eagle talon tsi awd.

i noticed that when i bought the car, the old owner had 2 predator tires at the front

and one x-ice (winter tire from mich) and 1 other branded tire on the back

how much does that affect the car and what is the side-effects or dmg?

cus i either buy 4 new tires or just buy 2 of those crappy tires to replace the rear ones. but i might want to wait till winter is over.

also anyone here from canada , toronto , markham area know where i can get parts for

the talon, i heard that the right spark plugs are hard to find.

ngk powers bpr6es right? but it has to be in a box package and not the plastic one?? i donno what difference that makes.

 

[flyinghighlm]

Well as far as all the differant tires goes, they all have differant tread patterns and react to road changes in thier own (designed) way. They can alsi cause your car to pull one way or the other, or act strangly when making turns...yes a tire is a tire and they go round and round but it is never a good idea to mix tires on a DD. The sark plugs you are looking for I got mine from Advance, they had to order them but they came in the next day.


Here ya go, got this off of Tirerack.com


As a general rule, tires should not be mixed on any vehicle unless specified as acceptable by the tire or vehicle manufacturer. Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes, and use identical tires on all of their vehicle's wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires, or mix run-flat tires with non-run-flat tires.

This is one of the reasons that it is desirable to have all of a vehicle's tires wear out at the same time. It's confirmation that the vehicle design, driving conditions and maintenance practices worked in unison to equalize tire wear and performance. It also lets drivers know they got their money's worth out of the current tires and allows them to choose a set of replacements that will either maintain the Original Equipment (O.E.) tires' capabilities, or help tune the vehicle's qualities to even better suit their needs.

Unfortunately wearing out all tires at the same time isn't always possible. Sometimes vehicle design, the use of differently sized tires on front and rear axles, insufficient maintenance and/or driving conditions conspire to prevent it from happening.

If a vehicle's tires don't all wear out at the same time, drivers are typically forced to decide whether they should purchase a new set of tires (forfeiting the worth of the two tires not fully worn out) or just a pair of replacements. While purchasing a new set of tires is best because it will maintain the handling balance engineered into the vehicle while restoring poor weather traction, it is also more expensive. And while purchasing a pair of replacement tires reduces immediate expense, it brings with it the options of choosing exact, equivalent or alternative tires.

Of the three, the best choice is to select the exact tire currently on the vehicle. This assures that the tire's physical dimensions, internal construction, tread design and tread compound are equal to the tires being replaced.

The second option is to choose equivalent tires from the same tire performance category that share the same speed rating, handling and traction characteristics of the original tires. While this isn't as desirable as selecting the exact tire currently on the vehicle, it can become necessary when the original tires are no longer available.

The third option, choosing alternative tires, should only be considered as a temporary solution in an emergency situation. Using alternative tires from different tire performance categories, with alternate sizes or different speed ratings can unbalance the vehicle's handling in poor weather or when pushed to the limit in an emergency.

Because tires play such an important role in every vehicle's comfort qualities and handling capabilities, it is always best to drive on tires that are identical in every detail, including tire brand, model, size and remaining tread depth. Anything else involves some type of compromise.

 

[Defiant]

1992 eagle talon tsi awd.

Terminally. Eventually, the constant-running of the viscous couplers will destroy them. Only buy DSM AWD tires in full sets. The DSM AWD setup isn't like any other vehicle's.

i heard that the right spark plugs are hard to find.

Complete bullshit.

ngk powers bpr6es right? but it has to be in a box package and not the plastic one?? i donno what difference that makes.

None that I've ever heard of.

 

[beating4g63s]

the bigger problem is different tire size. like 225/45/16 and a 225/40/16 can cause problems friend had a flat and ran a spare tire that was completely wrong size. and blew the rear end out after a few days. also that winter tire. I'd switch out fast. when it rains and your driving it may cause hydroplane easier, I ran that same tire on one rim on my n/t and spun out on the highway lucky enough I remembered the E-brake before hitting anything.

 

[VanIsleDSM]

no it's not a great idea, but it won't blow your viscous coupling as long as the different brand tires are the same size, wheneven you're not driving in a straight line some wheels are moving faster than others, having different tires with different wear on each still won't produce the difference in wheel rotational speed as taking a turn will.

 

[wolven91tsiawd]

Ok ive heard some conflicting stories about worn tires on my awd tsi.
ive been told that you will damage the driveline and LSDs in a awd dsm when you have 2 tires on front that are worn more than 2 tires on back.
ive aslo been told that it is ok to have differant tread debth on a DSM it is only the EVO III you cant do that on becouse of the center diff? example:front tires are new and back tires are 50%.
good tires are expensive,right now i can afford only 2.is it my best interest to wait to replace all 4 at once,or can I just put 2 new tires and drive it without damaging the driveline???

 

[yokotabrat]

All DSMs are equipped with a viscous coupled center differential, so any tire size difference between front and rear will cause a subsequent speed difference. This will put stress on the viscous possibly causing damage if the speed difference is great enough. Now, how much difference will lead to damage of the viscous is where I've seen debate. I've read as a general rule, no more than 3/32" tread depth difference, but that wasn't specific to DSMs.

I would say wait until you can afford 4 new tires of the same manufacturer and don't risk damage.

 

[JayRolla]

Ive always been told that it will damage your LSD by putting different size tires on. To be safe I would buy all 4. And not all DSM's came the vicous coupler, my buddys GVR4 does not have one.

 

[yokotabrat]

Jay, you're not getting the rear and center diffs mixed up are you? Not all DSMs have viscous rear diffs, but all DSMs have a viscous center. If they didn't there wouldn't be a way to actively distribute power from front to rear.

 

[JayRolla]

The transfer Case? I thought the visous coupler was in the rear diff and the center is the transfer case. I may be wrong, im not really sure.

 

[xveganxcowboyx]

Yokotabrat is right. They all have the viscous coupling differential in the the center. The rear differential is the one that was an option.

I have also read the different tires may damage the diff. When I bought my Talon the tires were different brands and worn differently. I drove it like that for a year before buying 4 new tires. No problems.

I've read that the difference has to be fairly large. I think I read 10%, but I don't know how much stock I would put in that. It seems risky. If I were you I would either save up and do them all at once or change 2 now and the other 2 very soon (don't give the new ones much time to wear). Sticking to one tire brand/model would be good. size can vary some between manufacturers.

What is your budget?

 

[yokotabrat]

Nope, the transfer case is nothing more than a 90 degree gear for DSMs. All it does is turn the output shaft toward the rear to the driveshaft. The center diff is in the tranny as is the viscous coupler for it. The rear also has a viscous lsd on some DSMs, but the rear diff is completely separate from the center.

 

[wolven91tsiawd]

i believe it would be best to just wait and get all 4.Since i have alot of time invested in the car i dont want to unjustly add to that time.i believe the dsm all had the center viscous diff and the LSD rear was an option.Not positive but would rather be safe than sorry.Theres another 3 weeks sitting for downtime.

 

[JayRolla]

Yea I didnt know the center diff was a viscous center diff. My mistake.

 

[ARTSUPRA]

Daem, going back 3 years ago

Anyways, I drove that car for over 6 months, then sold it and new owner drove it for at least a year, no problems reported.

 

[SnowBird]

Just rebuilt my car Ive never driven before, Im about to break it in Long story short. I bought the car all messed up from someone that shouldnt have owned it. Its a 90 AWD and it has 2 pairs of mix matched tires, they are all the same size but one pair is about 80% while the other is about 60%. Ive heard its not good to do this on an AWD unless you want to mess the VC up.

Soooo...

1) Is this a myth and it will be ok for awhile?

2) Should I pull my T-case and driveshaft and just roll around in FWD while I break in the engine? (car is ready to roll and I cant afford new rims/tires right now after all the money this project ate up.) Or will this just kill the VC just as fast?

 

[elfroggo]

You should be fine. Running different size tires or rims wouldn't be a good idea though.

No, you shouldn't pull your tcase and driveshaft for breakin

 

[1g_tsi_awd]

^^^^+1

You should be fine.

 

[SnowBird]

Good, thats what I wantd to hear, like I said, the tires are the same size, but you can tell by looking at them that 2 have been around the block a lot more than the other 2.

And would pulling my driveline cause my VC to burn up? I dont understand why you have to have the center diff welded to do it, because when a T-case goes bad the car is turned into a FWD, right? Or does it slip and shit? Maybe I should start this in another post.

Anyone first hand have any problems with running mismatched brand names or anything on an AWD?

 

[PieEyedPiper]

I'm going to go against the grain and suggest you not drive it until you have 4 new tires.

 

[No_Skillz]

It will NOT be fine. Get 4 tires, same size, same model, same manufacturer, brand new.

Think about it... even a tiny difference in circumference will be a huge factor when these wheels make several hundreds of thousands of revolutions on an average trip.