Tire Filter
September 15, 2011 7:54 AM Subscribe
I have a 2004 Jeep Liberty that needs new tires. The factory tires are 225/75/16 I have 4 brand new tires 2 are 225/60/16 and 2 are 215/65/16. What problems am I going to run into if I put the 215/65/16's on the rear and the 225/60/16's on the front? Are there safety concerns? are there Mechanical concerns?
Generally having mismatched tires on an AWD/4WD vehicle is really bad news because it means the diffs are turning constantly and wear down because the tires are turning at different speeds. The two sets of tires you have do have the same diameter, so you'll most likely be okay, but if it were my car, I would get in touch with a local tire shop and see if you can trade a set in for two to match the set you keep. Most tire places will give you some value for old tires, and if they are indeed brand new they may give you full value back. Explain your situation and your concern and I'm sure they'll either help you out or let you know if it won't be an issue.
posted by InsanePenguin at 8:12 AM on September 15, 2011
posted by InsanePenguin at 8:12 AM on September 15, 2011
I've always read that it is not a good idea to run different diameter wheel/tire combinations on an all-wheel or four-wheel drive vehicle. Even small differences, such as new tires on the front and older tires on the back are enough that AWD/4WD manufacturers recommend against it.
In your case the sidewall heights are 135mm for the 225/60/16s and ~140mm for the 215/65/16s or a ~10mm difference in the overall diameter between the two. That's may be within allowable spec for the Liberty but it seems to me that it is a lot of rotational difference for the transfer case to try and absorb. Best to seek what Jeep says about such a thing.
posted by bz at 8:13 AM on September 15, 2011
In your case the sidewall heights are 135mm for the 225/60/16s and ~140mm for the 215/65/16s or a ~10mm difference in the overall diameter between the two. That's may be within allowable spec for the Liberty but it seems to me that it is a lot of rotational difference for the transfer case to try and absorb. Best to seek what Jeep says about such a thing.
posted by bz at 8:13 AM on September 15, 2011
Damn, I screwed up, I was transposing tire numbers.
I change my answer, you need to get matching tires.
posted by InsanePenguin at 8:15 AM on September 15, 2011
I change my answer, you need to get matching tires.
posted by InsanePenguin at 8:15 AM on September 15, 2011
All of your car was designed to work together. The tires are a very important part of how your car handles, this includes stopping and weaving in emergency situations (like accident avoidance-which is much preferred over accident survival). By changing the height of your tires you are changing suspension geometry and suddenly the suspension doesn't work quite right anymore. Now the practical difference on something like a Jeep liberty with a 10mm change in tire diameter is going to be pretty miniscule and probably within tolerances for the vehicle (Jeeps are not sports cars and you are not doing track days with it, I hope anyway).
Different sized tires have a different number of revolutions per mile. When your front and rear tires are different sizes (or even worse the left and right sides are different) the differentials have to make up the differences between those rotations. The liberties have several different 4wd systems, some with center differentials, some without but either way it is going to put more strain on the system with different sized tires. The rotational difference between the two tire sizes is going to wear out your 4wd system faster however. And how much does a new differential cost as opposed to a new set of tires? Unless you have a good reason and know what you are doing trust the factory engineers for this, they generally know what they are doing and have set up the car to work with the sizes for everything set up like it rolled off the assembly line.
Another thing to consider is ABS systems. My understanding is they work on sensing the difference in rotational speeds between wheels and you would be introducing a difference in that speed. Once again probably not enough to make the system not work but it is still less than optimal.
You might also be able to sell the tires on craigslist. I see tires listed there all the time.
posted by bartonlong at 9:26 AM on September 15, 2011
Different sized tires have a different number of revolutions per mile. When your front and rear tires are different sizes (or even worse the left and right sides are different) the differentials have to make up the differences between those rotations. The liberties have several different 4wd systems, some with center differentials, some without but either way it is going to put more strain on the system with different sized tires. The rotational difference between the two tire sizes is going to wear out your 4wd system faster however. And how much does a new differential cost as opposed to a new set of tires? Unless you have a good reason and know what you are doing trust the factory engineers for this, they generally know what they are doing and have set up the car to work with the sizes for everything set up like it rolled off the assembly line.
Another thing to consider is ABS systems. My understanding is they work on sensing the difference in rotational speeds between wheels and you would be introducing a difference in that speed. Once again probably not enough to make the system not work but it is still less than optimal.
You might also be able to sell the tires on craigslist. I see tires listed there all the time.
posted by bartonlong at 9:26 AM on September 15, 2011
If your put different-diameter tires on the front and rear of your vehicle, and it has a conventional 4wd system, you will not actually be able to roll in 4wd on dry pavement. If you have AWD, you will merely heat it up and wear it out (and waste a crap-ton of gas in the process).
For the love of all that is holy, don't mismatch your tires.
posted by klanawa at 2:57 PM on September 15, 2011
For the love of all that is holy, don't mismatch your tires.
posted by klanawa at 2:57 PM on September 15, 2011
This thread is closed to new comments.
The 225/60/16's are about 1-2 inches in diameter smaller than your factory tires. I don't know if there is a safety issue, but your odometer will read incorrectly as each revolution of the wheel will take you ~5% shorter distance.
The 215/65/16's have same diameter issue as well as being 10mm narrower than your factory wheel. I don't know if it would even fit on your wheel or not, hopefully someone else can chime in.
posted by dabug at 8:12 AM on September 15, 2011