OK...here's one for all the automotive experts:
I got a flat on my Xterra this morning. Looks like its a razor blade, or a 1-2" flat piece of metal or something in the tread so apparently it can't be fixed...I need a new tire. Bummer, as the tires on the vehicle are only about 15 months old (~12,000 miles or so). They still have a LOT of life left in them.
The guy at the tire store is saying I should get 4 new ones because the tire diameter between the new ones and the old ones will be greater than 3/32", and I will damage my transmission/transfer case if I ever use 4WD for decent periods of time. Now, I can see needing 2 new ones, and keeping them either on the front or rear...but all 4 new? That seems like BS. ??? Seems to me tire inflation variation can cause more of a diameter increase that 12,000 miles of travel....but I admit I'm no expert and could be wrong.
So, what's everyone experience? Do I need 1, 2, or 4 new tires? Keep in mind, when I use 4WD it is mainly on the road (ya...I know that's lame) so it may be engaged for a while.
Thanks [thumbsup]
I would say you need two. What tire store did you go to? Schwab's? I only trust Les Schwab, with my tires.
Quote from: Sinister on April 02, 2009, 01:59:17 PM
I would say you need two. What tire store did you go to? Schwab's? I only trust Les Schwab, with my tires.
Ya, 2 I could see, but who knows.
Discount Tire. Les Schwab is WAY more expensive, and they only carry their brand. I like BFG or Bridgestone for all terrain tires. I checked around on prices when I got this set and Discount was the best.
Discount has actually been great...they rotated and balanced the tires for free for me last weekend, and this repair would have been free. I'm just wondering if the guy knows what he's talking about.
You need two new ones, and you need to get them from a different store.
I absolutely hate shit like this. Some douchebag is having a bad month, so he tries to up his sales thru deceit.
As a 4x4 owner since 1981, I can categorically state that the difference between new and 12k miles will never damage your transfer case or tranny. Period.
Oh, here comes my nurse with evening meds.
Quote from: Triple J on April 02, 2009, 02:31:10 PM
I'm just wondering if the guy knows what he's talking about.
That's why I like Schwab's; I trust their guys...and they have great tires.
Depends on the type of transfer case and the difference in tire diameter. If you have a center diff in the t-case you will be spinning up the gears the entire time you are driving. The circumference doesn't change based on tire pressure for a radial tire. How much difference between front and rear is acceptable? Hard to say. My Hummer eats front tires much faster than rears and it never seems to bother the t-case. Which is full time 4wd with a center diff.
I would say two at the most as well, but there can't be much difference in diameter at that mileage versus new.
If the vehicle has high miles and you can get one tire of the same brand and size I'd say screw it and just replace the one....
See if your tire shop has any take offs. I have always got tires for my Jeep this way. All the people that take off the OEM for something bigger save me a bundle of $.
Full size spare of the same make / model tire ?? If so... one new tire and the spare on an axle and the tire that was on that axle becomes the spare. ;D
Dang-sno_duc beat me to it!
If it was me, I'd only replace the one. I like to replace my tires in sets of 4 when I do, so in your case, I'd buy the one, and then swap all 4 when the other 3 are due. Keep the 4th as a spare if you need it.
I've replaced a lot of tires, and I've never seen a diference as small as 3/32nds make a lick of difference.
Let's say you have tires which are approx 29in in diameter, I'm just guessing based on your vehicle. At that size you're only talking about a .644% difference in circumference That isn't much movement in the differential. If your truck has a 5 ft wheelbase, that would be like you 2000 ft diameter circle all the time. You won't see any decernable wear.
Justin
Quote from: sno_duc on April 02, 2009, 04:29:30 PM
Full size spare of the same make / model tire ?? If so... one new tire and the spare on an axle and the tire that was on that axle becomes the spare. ;D
That would be nice, but this is the 2nd set for the truck and these are a bit larger than the previous.
I think I may just get two and make the extra one the new spare so my spare is the same as the tires I have now. My OEM spare is a full size tire...but it's still smaller by a bit than ny current tires. Of course it may not fit up under the rear of the truck, so I may just get one.
Quote from: silentbob on April 02, 2009, 03:13:27 PM
If you have a center diff in the t-case you will be spinning up the gears the entire time you are driving.
The circumference doesn't change based on tire pressure for a radial tire. How much difference between front and rear is acceptable? Hard to say. My Hummer eats front tires much faster than rears and it never seems to bother the t-case. Which is full time 4wd with a center diff.
How do I know what type of T-case I have? I have a mechanical lever inside (i.e. not electrical push button), but I don't have to lock the hubs.
May not matter...sounds like tire wear doesn't affect your Hummer though...which would seem to be a worse case with the center diff.
While diameter wouldn't change due to air pressure alone, wouldn't it change if the tire was underinflated so when it was loaded it squatted more and thus had a smaller effactive radius? ???
Quote from: Sinister on April 02, 2009, 02:48:23 PM
That's why I like Schwab's; I trust their guys...and they have great tires.
I hear ya, but for a couple hundred bucks I'd rather call them on their BS, but still save the money. I used to have some Schwab Wild Country tires on my old Chevy 1/2 ton and I thought they were crap. :-\
Thanks for all the help guys! [thumbsup] [thumbsup]
I'd say do what you want. The difference between a worn tire and a new tire can't be *that* much. At least not enough to cause a problem with the transfer cases. Maybe if you were in 4-wheel on dry pavement or something but under normal use I'd think you'd be fine ~
JM
I fairly certain Silentbob's example only pertains to the + 10,000GVW vehicles. In a passenger vehicle the only thing that makes any difference is the diff, not the T-case. if you have open differentials then it is no big deal. if you have a locking diff then it matters what type, a clutch style locking differental will get hot much faster with the difference in tire diameter any other the clutchless type will simply eat up the tires. I used to be a Schwaby and things have changed, I do not like them anymore.
Quote from: Mother on April 02, 2009, 06:36:01 PM
I fairly certain Silentbob's example only pertains to the + 10,000GVW vehicles. In a passenger vehicle the only thing that makes any difference is the diff, not the T-case. if you have open differentials then it is no big deal. if you have a locking diff then it matters what type, a clutch style locking differental will get hot much faster with the difference in tire diameter any other the clutchless type will simply eat up the tires. I used to be a Schwaby and things have changed, I do not like them anymore.
Definitely open diffs.
if it is open diffs and a true 4x4 and not an all wheel drive with a 4x4 lock (like on the newer fords) then just by 1 tire. you may wear them a touch faster but you won't hurt anything.
Now for my disclaimer. All I know is standard part-time chain and gear drven tranfercases with a planetary gear set, your basic rear wheel drive with a disconected front drive axle.
Anything fancy like a hummer/subaru/newer ford then I would just sell back the 3 and buy 4 new ones.
Just get the one tire unless you have a limited slip of any kind in that thing. This tire guy is full of shit.
utter bullshit
replace the tires on the same axle, that's all you need..
On some late model full time 4 wheel drive vehicles perfectly matched tires are a must. Yours is not one of them. If you are anal, replace the two on that axle. If not, just replace one.
Quote from: howie on April 02, 2009, 09:45:53 PM
On some late model full time 4 wheel drive vehicles perfectly matched tires are a must. Yours is not one of them. If you are anal, replace the two on that axle. If not, just replace one.
Agreed [thumbsup]
A few years ago I was in a snowstorm on my way down from Denver to Colorado Springs. The owner of the Subaru I was riding in got spooked when the Nissan Murano immediately ahead of us suddenly spun into the median. She pulled over and refused to go any further. When we both got out to walk around and switch seats, we were having to hold onto the car to not fall on our asses.
So I took off (not quickly) and the car was all over the place. I realized she'd had it in 2WD the whole time. On a Subaru, that means FWD which is nice. This was an older Loyal so it had an engagement stick tx instead of the full time stuff we see now. As it was shift on the fly and I was only doing like 15MPH I went ahead and shifted into AWD. Things got even hairier. The front and rear weren't working together and it seemed like the viscus coupling (Subaru and Audi used these as a kind of limited slip) was forcibly disconnecting and reconnecting. It was seriously unnerving. I ended up shifting back into FWD as the car was more manageable that way.
When we got home, I told Sue to take in her car and have the system looked at. Something was not right, I said, the car can't use AWD.
Ends up she'd replaced the front two tyres, and the difference caused the AWD system to fail due to the fact that the CD spins the front and rear at the same rate, requiring the tyres to be the same size. So the front was pulling the loaded rear and forcing a viscus disconnect, even on a road that was soo slippery I couldn't walk down it. There were crashes every mile.
Moral of the story is, if you have different diameter tyres on the front than the rear, YOU DO deplete the function of your drivetrain and make it all but useless in 4WD ON ROAD. The question then becomes, does that matter to you? Do you use 4WD on road?
This is actually a sort of funny read on here, as I'm pretty sure these same respondents would clammer to tell you you shouldn't just replace one tyre on a bike..... But to refute all the shenanigans claims, I can tell you from first hand experience that using different diameter (even older and newer) tyres ON ROAD can do damage to your driveline that will make tyre replacement seem inexpensive.
All the same, were it me, I'd only replace two. Then all four when the oldies wear out, and keep the newer two as spares. But I, despite living in Colorado Springs, am unlikely to use 4WD on the road this late in the season.
Quote from: Smokescreen on April 03, 2009, 06:53:52 AM
Ends up she'd replaced the front two tyres, and the difference caused the AWD system to fail due to the fact that the CD spins the front and rear at the same rate, requiring the tyres to be the same size. So the front was pulling the loaded rear and forcing a viscus disconnect, even on a road that was soo slippery I couldn't walk down it. There were crashes every mile.
different size tires? of course it was weird.
and
it was in one of those fancy subaru systems.
not a standard 4x4
also
I am one of those that will run a front through 2 or 3 rears
:-)
Quote from: ducatizzzz on April 03, 2009, 07:17:47 AM
different size tires? of course it was weird.
No, the same make and model tyre, just newer, as she'd got in the habit of replacing one end then another as it wore out.
Mother- the "fancy" Subaru system on the Loyal is a transfer case with a center viscus diff. Not dissimilar (save for the center viscus diff) to the systems used on any other vehicle with a lever opp transfer case. So in this case, the only difference between the Loyal and a standard 4X4 would be the transfer case going FWD instead of RWD in 2W mode.
While on my CJ7's Dana 300 transfer case I wouldn't even think twice about beating the hell out of it (I used to leave the hubs engaged despite the Detroit locker in front), and I'm sure Nissan uses plenty durable parts, I still hold to it being a bad idea if you plan to use 4WD on road. This is doubly true if the ExTerra is outfitted with any kind of dynamic vehicle control, which will be continuously monitoring wheelspin on each corner and will react to varying wheel speeds in a straight line and in turns.
My ExTerra experience was limited to two long term magazine ExTerras, but the last one I drove was tempermental about tranfer case activity at the best of times.
You know the saying, "oil's cheaper than parts"? this is one of those times. Tyres are cheaper than hard parts. Though I suppose only Triple J will be responsible for the cost of failure in this case. It's not like it'd cause an accident. Just possible damage to parts.
Like I said, I'd replace two and avoid 4WD on roads.
Quote from: Smokescreen on April 03, 2009, 07:53:36 AM
No, the same make and model tyre, just newer, as she'd got in the habit of replacing one end then another as it wore out.
yeah, i am surprised most ppl don't know you are supposed to rotate about every 6-8 k miles
the warranty on most tires requires you to rotate and to record it. we got new Toyos on the wife's car and one developed a bulge. i called them for warranty replacement and the first thing the girl asked was "do you have the rotation records? "
YES I DO.
I know to do that. Every other oil change the tires get rotated ~
JM
It's an easy thing to forget. I rotated my Jeep's tyres regularly, because they never wore evenly (fr v. r) but with my WRX I only did front to rear rotations. Not the crossways bit. The WRX wore pretty evenly from side to side.
Thanks for all the input. ;D
I'm gonna get two and put them on the front (where the flat is anyway). I'll just leave them there until Fall...so they'll probably be about the same wear as the rears (or at least a lot closer) when it's possibly time for 4WD in the snow again. My Xterra definitely eats fronts faster than rears. I do use 4WD on the road when it snows, so if it feels like there is a problem then I'll buy all new ones and consider it a lesson learned.
BTW...it's an '04 Xterra...it doesn't have any fancy electronic driving aids like traction control, stability control, etc. I've also never had a problem at all with the T-case.
I always replace 4 tires at a time, but damn...these are only a year old!
Quote from: Mother on April 02, 2009, 08:08:53 PM
if it is open diffs and a true 4x4 and not an all wheel drive with a 4x4 lock (like on the newer fords) then just by 1 tire. you may wear them a touch faster but you won't hurt anything.
Dumb question alert: How does one know if one has open differentials? (I have an '01 Chevy Silverado Z71)
Chances are you're LSD or similar out back and open up front if all is stock
JM
Quote from: the_Journeyman on April 03, 2009, 08:33:49 AM
Chances are you're LSD or similar out back and open up front if all is stock
JM
They really put LSD's in those? Your front is certainly open. Put it on pavement and gun it. If there's only one skid mark it's open in the rear.
And to the OP - 4x4's that are all open don't need all the tires to match exactly. As Mother pointed out, the AWD and 4WD systems work a bit differently. there's no computer to jack up your 4WD system. It's not a bad idea to replace two at this point, though, since you should have a matching spare which you currently do not. So here's another vote for ditching your off-size spare and keeping your good front as an extra.
Quote from: DCXCV on April 03, 2009, 08:41:09 AM
They really put LSD's in those? Your front is certainly open. Put it on pavement and gun it. If there's only one skid mark it's open in the rear.
And to the OP - 4x4's that are all open don't need all the tires to match exactly. As Mother pointed out, the AWD and 4WD systems work a bit differently. there's no computer to jack up your 4WD system. It's not a bad idea to replace two at this point, though, since you should have a matching spare which you currently do not. So here's another vote for ditching your off-size spare and keeping your good front as an extra.
Possible. My Dad's stock '99 Silverado had a type of delayed locker in the rear, and many of them have something to help out on the rear axle. Be it LSD, posi-traction etc.
JM
Quote from: Sinister on April 03, 2009, 08:23:34 AM
Dumb question alert: How does one know if one has open differentials? (I have an '01 Chevy Silverado Z71)
Go wheelin' and get a tire off the ground. If the one that is off the ground spins, and the one making contact (same axle) remains useless as a fart in a windstorm...that axle has an open diff.
My '94 Chevy 1/2 ton had open diffs front and rear. The rear might have had some half ass limited slip or something, but it was fairly worthless off road. I'd have to shift into 4WD pretty quickly off road, whereas my buddy in his Tacoma with an electric locking rear didn't have to shift until things got fairly hairy.
The easiest way to tell if your vehicle has open difs is to look at the monrony. LSDs cost moneys. They cost more than lockers usually, as LSDs have more moving parts, and have to be built to not wear out despite allowing slip. A locker is highly unusual and on a road goer not a great idea in the rear and you're more likely to drag your outer tyre than actually get the ratchet effect that most manufacturers claim.
Triple J- Good call. I doubt you'll run into any problems.
Quote from: Sinister on April 03, 2009, 08:23:34 AM
Dumb question alert: How does one know if one has open differentials? (I have an '01 Chevy Silverado Z71)
Jack it up and spin one wheel by hand. If the other wheel spins in the same direction you have a LSD if it spins backwards you have an open diff.