New rear tires with old front tires ?

[Scot]

I have nitto nt05's on my 2009 ACR. I just replaced the rears with new ones but kept the old fronts since they have plenty of tread. Now the handling seems goofy. Tire psi is 32 all around. Is that normal? My fronts still have half tread so I don't want to replace them.

Anyone have any knowledge about mixing new rear tires with old fronts?

[Uncle Paul]

Not just the tread depth, but also the age of the tires.

New tires tend to stick better than older tires.

[jvm728]

correct. after time the rubber gets weak (dry rotting/cracking?). If you don't drive much, thats pretty susceptible after 6 years.

[FrgMstr]

You obviously don't turn enough and that was what the ACR was built for. You should immediately turn it over to me so we can get those fronts to match the backs in tread depth. ;)

[Vprbite]

As I understand it, mismatched tires is bad news on most cars but especially bad news on our cars. Like front page headline bad news. Age will kill a tire just as badly as mileage. I don't know where you are located but in drier climates it goes even faster. Out here in Arizona, I say 4 years is a good rule for tire replacement, but that you can go 5 in a pinch. Any more than that and you are asking for trouble. If you are in an area that isn't so dry, you could probably push those numbers a year but I wouldn't go any longer than that. Please be careful. Bad tires could severely hurt you or worse.

[Scot]

my front tires are roughly 15 months old with about 9k miles on them..... I think I may order new fronts since the back tires are only 2 weeks old now. thanks for the replies! :)

[Nine Ball]

I wouldn't worry about it for tires at 15 months. The "goofy" handling might actually be because you were used to the worn out tires, and now it actually handles better. I usually run my rear tires at 25 on the street, for more grip. On the road course, I set them at 28-29 cold.

[uvbnbit]

understeer, tendency to feel "push", better than oversteer imo

[Vprbite]

Sorry, I didn't realize they were only 15 mo old. I saw you had a 2009 ACR and assumed they were stock. That is why I said it was dangerous. At 15 mo old. You are probably experiencing what NineBall said. New rubber makes any car handle better. So you are probably feeling good handling mixed with not as good.

Still, some of the more educated people can chime in. I feel like I was told never to mix tires on these cars but since you have the same model tire, it may not be an issue being that the fronts are barely over a year old. Now if we could only figure out why the rears wore down so quickly. It's a smoky mystery : )

[BlknBlu]

How many times have they been heat cycled?

Bruce

[Scot]

Sorry, I didn't realize they were only 15 mo old. I saw you had a 2009 ACR and assumed they were stock. That is why I said it was dangerous. At 15 mo old. You are probably experiencing what NineBall said. New rubber makes any car handle better. So you are probably feeling good handling mixed with not as good.

Still, some of the more educated people can chime in. I feel like I was told never to mix tires on these cars but since you have the same model tire, it may not be an issue being that the fronts are barely over a year old. Now if we could only figure out why the rears wore down so quickly. It's a smoky mystery : )


ahhahah...people at my work are like "how did they wear out so fast"... um... it has 600+ hp....... of course these same people are like "I get 40,000 out of a set of tires".... doh.. :D

[CarolinaViper]

Who out there changes their front tires every time they replace their rear one....not many I bet. As mentioned in an earlier post, date of manufacture as well as actual tread wear is important. More than likely, you will get almost twice the miles on the front as you will get on the rear, unless the tires are 5-6 years old seems to be a waste of money to throw out the front tires every time you replace the rear.

[Scot]

How many times have they been heat cycled?

Bruce

the new tires I have just driven here and there but not any long distances.... the old tires I did take to the track 1 day so they have maybe 100 track miles on them along with 9k street miles...... I guess I am hoping in the next couple of weeks the backs heat up and the handling becomes more predictable... it feels twitchy so I am just driving slower around turns to not risk it.

[mjorgensen]

I wouldn't worry about it for tires at 15 months. The "goofy" handling might actually be because you were used to the worn out tires, and now it actually handles better. I usually run my rear tires at 25 on the street, for more grip. On the road course, I set them at 28-29 cold.

This^^^ A deaper tread (new) will have more "squirm" then a worn tire so feel and handling will be different.

[FrgMstr]

Who out there changes their front tires every time they replace their rear one....not many I bet.

I always wear the fronts down to the wear bars or worse before the rears and I always replace all four at the same time.

[JonB ~ PartsRack]

I have nitto nt05's on my 2009 ACR. I just replaced the rears with new ones but kept the old fronts since they have plenty of tread. Now the handling seems goofy. Tire psi is 32 all around. Is that normal? My fronts still have half tread so I don't want to replace them. Anyone have any knowledge about mixing new rear tires with old fronts?

SCOT! Thank you for again confirming a 'caution' that I have been warning and posting about for decades: Mismatched Traction. Your new rear tires are now writing checks that your old front tires cannot cash.

The problem is NOT when you are paying 95-100% attention at the track....you'll just push like a pig, and be aware and control it. The problem is when you get surprised on public streets, highways, and have to 'go evasive'..... you will over-correct and under-steer and hit the ditch or worse.

Vipers on average need 2 sets of rears for every set of fronts.... but if you try to squeeze every 1/32 of tread out of old, hard, heat-cycled front tread, and harder sidewalls and carcass to boot, you ARE taking additional risks.

Sell those 'good tread' fronts on Flea-Bay, they fit a lot of cars, and drifters want hard tires! Really!

http://www.viperpartsrack.com/tire-wheel-tread-safety-viper

[Alex Mills]

What about the reverse? I guess I have a bad alignment/camber (which I'll get fixed) as the insides of my front have worn down, especially the driver's side. My rears still have plenty of life left in them (only 2 years old). Seems a waste to toss perfectly fine tires just because I happened to wear out the fronts before the backs.

[uvbnbit]

oversteer

[JonB ~ PartsRack]

What about the reverse? I guess I have a bad alignment/camber (which I'll get fixed) as the insides of my front have worn down, especially the driver's side. My rears still have plenty of life left in them (only 2 years old). Seems a waste to toss perfectly fine tires just because I happened to wear out the fronts before the backs.



Cars with a performance alignment (negative camber) will wear out their inner shoulders faster, because the 'tilt' of the wheel ensures you are flat-footed (bigger contact patch) when cornering. When you need it most. So Negative Camber 'sacrifices' the inner shoulders to get better handling. A good trade! It is normal to see the drivers side wear out first as you note. WHY? The Driver's weight is there, often solo.

Negative Camber usually helps fronts and rears 'expire' closer to the same time. Unless you track or X a lot. OE alignment eats rears, saves fronts, sacrifices handling.

New Sticky tires up front will give more grip there, making the rear, harder tires feel 'twitchy' or oversteering as Bit says. In this case your front, sticky tires are writing checks that your rear tires cannot cash. And your hands 'feel' hooked up, but your SOTP butt feels loose.....

[ViperGTS]

Shy of buying 4 new tires?
Buy a PRIUS.
A Viper is the WRONG car for you!
Clear enough?
:t0152:

[Alex Mills]

Cars with a performance alignment (negative camber) will wear out their inner shoulders faster, because the 'tilt' of the wheel ensures you are flat-footed (bigger contact patch) when cornering. When you need it most. So Negative Camber 'sacrifices' the inner shoulders to get better handling. A good trade! It is normal to see the drivers side wear out first as you note. WHY? The Driver's weight is there, often solo.

Negative Camber usually helps fronts and rears 'expire' closer to the same time. Unless you track or X a lot. OE alignment eats rears, saves fronts, sacrifices handling.

New Sticky tires up front will give more grip there, making the rear, harder tires feel 'twitchy' or oversteering as Bit says. In this case your front, sticky tires are writing checks that your rear tires cannot cash. And your hands 'feel' hooked up, but your SOTP butt feels loose.....

Ah, that makes perfect sense, especially considering my tires have 23,000 miles on them now, mostly via road trips with just me in the car.

Thanks as always for the info, Jon. You're the best!

[ACR Steve]

I get 5,000-7,000 out of a set no track driving consider yourself lucky buy the fronts

[JonB ~ PartsRack]

Ah, that makes perfect sense, especially considering my tires have 23,000 miles on them now, mostly via road trips with just me in the car.

Thanks as always for the info, Jon. You're the best!

We SELL Tires Too !!

[johns viper]

i have a 2004 srt and the past owner lowered it 3 inches and put after market rims pirelli p zero rossos the rears are 345-25-20 i burned thru a set in 3000 miles. where ever i drive i get rubber up the bumper. other vipers do not have this issue. is that i lowered it or because they r to wide? thanks