not sure, but my best quess is that if you have to have the mismatched set of tires you might want the better tires (not sure which those are) on the front. Anyone else?

well, i have two cents to add to the pot..

i've blew acouple tires on my car, since she's acouple years old now and i had a distinct impression from the dealer that i did have a tire warranty...

the first tire i blew was patched, and i was told there was no warranty..
being the moron i am, i didn't pull out the file on my car and read all the documents, but just dished out some cash for a new tire.

i recently wanked up my undercoating. the dealership went belly-up and i found out i couldn't get the undercoating touched up till it was back in business. after the dealership re-opened, they informed me i had to call the undercoating co. and ask if my warranty was completely void. after i did so, the undercoating co. told me some big story (i'll save you the blah blah) and said something about my "rims and tires". when i asked for details, they told me that my tires were under warranty through them.
3 tires after the fact, i find this out.

boooooooooo

so the moral of the story kids, is read all the documents because the people at the dealership only tell you their part of the story, not the packages they offer...

;)

I did some lookin' on the subject. Seems thT on a front wheel drive car, mismatched tires won't cause as much problems as on other setups since the rears are really just along for the ride. Saw a test of mini-spares on front, rear and awd cars. A donut anywhere on a rear drive or awd horribly compromises performance, as does a donut on the front of a front drive car. Stick a donut on the rear of a front-drive car, though...and slalom times are nearly the same! :confused:

So...put your better tires on the front and the lesser on the rear.

Which Kumhos? Ecstas?

--Dean

they are the:
205/50ZR-16 18W B Kumho Ecsta Supra 712

thats what the receipt says exactly

ANyone know if Kumho Ecsta Supra 712's are any good? theyre $88.00 USD a tire.


BTW, thanks to everyone for all the feedback, i also think im just gonna keep the new tires in the back

Well, if they're Z rated, I would put them in front. Our SP5000s are V rated (Z-rated tires should have better grip)

i'm surprised your ABS light isn't on, with those tires having a larger rolling diameter. Usually the system will sense the difference in wheel speed and shut the system down. But if it hasn't - it's not sensitive enough (which is good in your case).
If anyone cares: NEVER do this on an AWD, or you'll pay for it.

LooseCannon, could you enlighten us by explaining why would the ABS light go on because of wheel speed difference? I mean, lets say when you make a left turn, the wheel speed of the right wheels will be faster then the left wheels because of the different circumference. Would the ABS light go on then? :)

i would if i didn't think you were being sarcastic
tell me, how do you think abs works?

Hehe, maybe i'm wrong, but i always thought that ABS works by detecting if the wheels locked or not. If it detects a wheel is locked, it will "release" the brake for a split second and re-apply again.

Just never heard that it's wheel speed difference toggled. Besides, it's called ABS because the full name is Anti-lock Braking System.

Of course, I could be wrong. :)

so how does it know when the wheel is locked up?

When it detects there's no wheel movement (or when the RPM of a wheel is 0), i guess.

exactly. with something called a wheel speed sensor (WSS). these sensors are located at all four wheels. with the system being computer controlled, it is constantly monitoring the speed of each wheel for differences (usually system does not become active until 5-8kph, sharp turns are generally under this speed :p ) I have already disabled my system a few times by pulling the hand brake in the snow. But it resets itself the next time you start the vehicle and it sees all wheels at the same speed.
enough for now.

My ABS (well...the EBF system actually) kicks in when I make a full lock turn and apply brakes...hence the system kicks in while the wheels are turning, not stopped. Try it in a parking lot sometime...low speed, turn the wheel all the way and apply light brake pressure. You'll feel and hear it. If it would wait until the wheel actually locked, then it wouldn't be anti-lock brakes, right?

LooseCannon is correct about rotational difference causing the EBFS to alert, but the difference between tire sizes is so slight and the difference constant...therefore the EBFS ignores it.

Put it this way...if it were sensitive enough to alert on tire size differences, it would freak when you had a mini spare on, wouldn't it?

--Dean

it really all depends on how sensitive the system is. mazda - i have no idea of the sensitivity, but as a GM mechanic - our systems can notice even a different make of tire that claims it is the same size. (i don't have to explain that do i?) as for the spare, most manufactures mini spare has the same outside rolling diameter so it shouldn't change anything.

Dunno why, but odd tires never upset my ABS Mazdas...but maybe they just have it dumbed down to avoid warranty issues. My mini-spare is definitely a different circumference. I gotta look into this...

--Dean