New tires NOT transmission (I hope)

I have a 2002 Ford Explorer Eddie Bauer.Have never been in a forum before so forgive me if I am in the wrong place.
I had two back tires replaced. Of course they do not make or so I was told the same as the front ones anymore.
Long story short.Drove straight across the road for a quick stop. Left for home and when I accelerated it was as if my car was stuttering for lack of a better word. It has never done this before. It seems to stop around 50 mph. Took it to our mechanic,he drove it and said it was the transmission. Took it back to tire shop and of course they say the same thing and that the tires are fine.
I find it very odd that all of a sudden first time I accelerate my transmission is messing up.
I looked up specs of both kind of tires.I hope I can put them on here.Anyway I think it has something to do with the tires.I may be a woman but I am not stupid.It is just to much of a coincident.
I think the links is all I could send.I hope you can compare from here.I have been working on this all day.
http://www.tirerack.com/tires/tires.jsp?tireMake=Yokohama&tireModel=Geolandar+H/T-S+G051

http://us.coopertire.com/Tires/Sport-Utility/DISCOVERER-H-T-PLUS.aspx

Yokohama is older ones on the front.Cooper is new ones on the back.
Tires or transmission??
Thank you for your time and help.Meanwhile I am stuttering down the road.

 

[ntex]

That is strange,but my pickup did the same thing last summer. i took it to my mechanic first thing he did was check the air pressure in my front tires one had none and one had 5lbs. the rear tires were fine. i explained how come the tires are not flat with no air in them he said light truck weight and heavy sidewall . i don't know but he fixed it.

 

[swshawaii]

(AWD) All Wheel Drive? If so, were the new rear tires the same DIAMETER as the front? (+/- 3/32")

http://www.explorerforum.com/forums/showthread.php?t=289260
http://www.explorerforum.com/forums/showthread.php?t=367412

http://www.miata.net/garage/tirecalc.html

 

[ntex]

Why would the stuttering seem to stop at 50 mph?

 

[renabell]

I have no idea why it seems to stop at higher speeds.
I can not find the diameters.
Is AWD & 4x4wd the same? Mine has 4x4.
I am calling a Ford dealership tomorrow in hopes they could tell me.I .bought these from Discount Tire.Even on their website it does not list the tire for a explorer,a expedition but not explorer.
I am giving up tonight.Been at this all day.
Thank you and I'll let you know if I find anything out.

 

[explorersport24]

Do you have the 4x4 auto button? The different size tires between the front and rear could cause the 4x4 to engage because the system thinks the rear tires are slipping since the front tires are at a (slightly) different speed than the rear. On my second gen the 4wd will not engage after you get above 55 mph or so. That could be why you don't feel the stuttering above 50 mph.

 

[renabell]

WOW that has got to be it!! Makes perfect sense.I do have 4x4 auto,4x4 high,4x4 low.
I did manage to find Revs. per mile(?).Front ones 702 New back ones 684.
I was told they do not make the front kind anymore.Guess that means I have to buy new front ones too? I don't know if I believe what they say now.They should have known better. They are loud too. I read where someone bought some brand (don't remember which) and it drove so smooth & quite. Mine has never been smooth or quite.I have really been disappointed in it.
Could it have damaged something now?
Thank you so much! Now I have some ammo cause I know they will argue with me.The two tires totaled to 239.12.
Thank you again.You made my day.

 

[swshawaii]

For future reference the easiest way to find the ORIGINAL tire size is the drivers door pillar sticker. Tire size is always molded in the tire sidewall such as 245/70-16, 265/70-17, etc. Another source for build specs is FordEtis by clicking vehicle, entering your VIN, and clicking minor features. Try this link, it's really cool!

https://www.etis.ford.com/

 

[explorersport24]

Are the front tires 245/70R16 and the rear tires 245/75R16?If your tires are in fact two different sizes front to rear, which based on your revs. per mile, I believe they are, than you will need to get matching fronts. It appears the yokohama's are 29.6" in diameter and the Coopers are 30.35. That is a difference of 24/32" which is out of the accepted range of +/- 3/32", as noted by swshawaii. I am fairly confident this is your problem. As for damaging something I cannot comment, since I do not have much knowledge of the third gen transfer case;hopefully someone who has a 3rd gen will chime in. Good luck with getting the issue resolved and I hope this helps!

 

[renabell]

No both tires old and new are 245/70R 16.
I am headed to the tire store in just a few minutes.I'd love to get the Michelin LTX but it is a little out of my price range.We'll see what happens.Considering I would not have taken my car to be worked on IF they had done a better job I would have an extra $400.00. That is how much my bill was from the mechanic.

I just want my Explorer to run properly and have a quieter, smoother ride.

One more question please. I do have 4x4 high,4x4 auto & 4x4 low buttons.Does that mean my car IS or IS NOT considered an all wheel drive?

Thank you.

 

[renabell]

Well guys I'm back. I must say Discount Tire was (of course) very apologetic and more than happy to do whatever I wanted. That worries me a little bit.Hope there is no damage.
I got Michelin LTX all the way around.Total was $329.00.
Smooth as silk!! I am elated and feel like I got a good deal.
Thank you all again for your help.

 

[swshawaii]

As usual, you get what you pay for, especially tires. Congrats, you now own one of the most highly regarded tires EVER made.

 

[toypaseo]

I must say Discount Tire was (of course) very apologetic and more than happy to do whatever I wanted. That worries me a little bit.

I would not worry about that. Every Discount Tire I have dealt with have been very helpful and presented above average customer service.

 

[renabell]

The Saga Continue......

UN-BELIEVABLE!

My relief that everything was fixed did not last long!! I am just disgusted and do not know what to do now. Will it ever end???

At about 30mph there is a little vibration and then again at 50mph. Also a recurring thumping sounds like (in my little mind) maybe a part of the drivers tire has something on it in a fixed place and when it rolls back around it makes the sound again.

Surely,surely it is not a tire!! I am not crazy(no matter what people say) Something is still off. It definitely is not the slipping,grinding sound as before but I can't even enjoy my supposedly smooth riding tires.

So what now? Mechanic or tire shop?? It is literally making me sick.

 

[Cstoliker]

This may sound too simple but check your lug nuts. You might think a facility that specifically does tires all day everyday would be good at it but you'd be wrong.
If they were tightened not enough or in circular pattern they can work themselves loose.

If you have 4wd auto, hi&lo then you have 4WD.
AWD and 4wd are compleaty different animals. The difference is when you turn left or right the front wheels have to turn a little faster then the rear because they have more ground to cover (this is why we have differentials).
4wd (hi or low range) locks the front and rear axles together with a gear and does not allow them to turn at different speeds. It is the best system for off road or extreme weather but causes binding, noise, tire wear and even mechanical damage when used on surfaces where all your wheels have traction. The "auto" function engages the gear only when traction loss is detected but the abrupt engagement can often cause a loss of traction on the other axles.
AWD uses a viscous clutch that provides resistance to the front & rear spinning at different speeds but does allow it. It's a better system for moderate conditions.

Both systems are not JUST to give you traction when accelerating. When your front and rear wheels keep each other in check, a temporary loss of traction buy one or even two wheels recover quickly before it turns into a full slide helping in all aspects or driving.

Basically AWD keeps you on the road, 4WD lets you go off it.