i have 2 different kinds of tiress on my jeep and was told not to put it in to 4 wheel drive now it that right or can i put in 4 wheel with out any problems at all?
What’s IMPORTANT is that all 4 tires are the same SIZE…So when they rotate, they all cover the same distance…
Usually Caddyman is pretty good, but on this one, he got it wrong.
While you would think that “Size” also means “dimensions”, there is not only enough slop in the “size” part that would cause problems for 4X4’s and AWD’s, but there are no laws or regulations that say that a tire of a certain “size” has to be those “dimenions” - and in fact, there are numerous cases where tires were deliberately made to dimensions different than indicated by the size.
That’s why all the tire manufacturers recommend that on 4X4’s and AWD’s that ALL tires be the same size, same make, same model, same state of wear. That insures that the rolling diameter is the same. Do otherwise and you risk a very expensive repair! Trust me, I know. I just paid 10K for a Caddy that had different diameter tires!
Oh, and I forgot to mention handling balance. Different tires have different handling characteristics, so you’ll want to keep the tires all the same for that reason as well (and that applies to FWD and RWD’s, too!) What you don’t want to happen is to discover in the middle of an emergency manuever that your tires are less than predictable.
In addition to Capri’s comments, I would add…
Since you said “put it in 4 wheel”, I’ll assume that your Cherokee is not the constant 4WD version.
That said, if your differing tires are on the same AXLE, you should be fine - as long as you leave it in 2WD. 4WD will indeed cause issues. You can even rotate them, just keep the same sizes on the same axles.
With winter coming (actually here in some parts), you may be tempted to run 4WD. Don’t. Not until you replace all 4 with the same everything, as detailed by Capri.
Its the HEIGHT of the tires (all need to be the same) you should be concerned with so the rotation is equal.
These guys drink too much coffee
essentially all four tires should YES be the same size
“Its the HEIGHT of the tires (all need to be the same) you should be concerned with so the rotation is equal.”
Nope, they need to be the same circumference, not height. A low tire will have a very different height, about the same circumference.
“but there are no laws or regulations that say that a tire of a certain “size” has to be those “dimenions” - and in fact, there are numerous cases where tires were deliberately made to dimensions different than indicated by the size.”
My BS alarm went off on that one…Tires are manufactured to standardized dimensions based on their SIZE markings. There is a LITTLE leeway between manufacturers and type of tire, but for the most part dimensions are held pretty close to avoid speedometer and clearance problems…
A P-225/60/16 marked tire will be very close dimensionally to every other tire marked that size. Now, there ARE some fussy AWD vehicles that demand a MATCHED SET of four IDENTICAL tires…Jeeps have never been that fussy. A part-time 4WD system should NEVER be driven in 4WD on dry pavement…The driveline is guaranteed to get bound up…These systems demand that the surface being driven on allows for some tire slippage so the drivetrain can stay “relaxed” and free-turning…
Texases…the circumference of two tires regardless of rim size, having same height on the same vehicle, WILL be the same. 265/70/16 has the same approximate circumference and height as 265/65/17 for example. A lower profile tire can have the same diameter as a high profile tire if it’s width is greater if the rims are the same size. In this case 265/70/16 would be about equal in diameter and circumference to 245/75/16.
The diameter of the tire determines it’s height and the pi times the diameter is the circumference. That is the critical part of 4 wd consideration. That said, traction differences on a raised suv subject to increase rollover chances, should be as close as possible.
That is why ALL cars should be matching in tire size in all measure ments and tread wear and type. In addition, different tread designs could have different tread depths in tire models which would make for different diameters, even if the indicated sizes were technically the same as Caddyman states.
Sorry, Caddyman, what I stated is correct. Spend a little time on Tire Rack.and look at the diameters published there. You’ll find plenty of variation.
Edit: I did a quick look to make it easy for you. Trying the size you mentioned: 225/60R16 - compare the Michelin Harmony (26.4") to the BFG Premier Touring (26.8") That’s 0.4"!!
While tires are standardized and there are a ton of reasons why tire manufacturers shouldn’t deviate from the target dimenaions, there is nothing to compel them to do so.
Further, the standardizing organizations allow a 3% deviation in diameter - which is HUGE as far AWD systems are concerned.
Plus, there have been situations where are a vehicle manufacturer needs to have a tire of certain dimensions which are non-standard - and they’ll ask their tire supplier to work with them. Yes, that creates one of those odd and potentially bad situations - and it is pretty rare - but it has been known to happen.
nICE TRY TEX BUT NO CIGAR
“Edit: I did a quick look to make it easy for you. Trying the size you mentioned: 225/60R16 - compare the Michelin Harmony (26.4”) to the BFG Premier Touring (26.8") That’s 0.4"!!
0.4" is NOTHING…That’s like comparing a new tire to one that is half worn out…Well within the tolerance of a Jeep Cherokee to absorb…(but apparently not a Subaru or Audi)
Puffer, the OP has never returned. This thread has lost its purpose…
0.4" is PLENTY!!! - and perhaps that is why you were giving the answers you were giving.
0.3" was enough to do in a 2008 AWD Caddy!! And the diameter tolerance of a Subies has been reported as little as 1/8".
- and that’s where I am coming from.
dagosa and badbearing - A tire on a car can have VASTLY different height (ground to top of tire) depending on its inflation. Right?? The circumference will differ little though. That’s why mounted height (ground to top of tire) is NOT a good indicator.
What do you mean by height?
I get what you are saying, but mounting height which is the diameter of the tire and related rolling circumference are directly related too. Tire deflection from low pressure will decrease the rolling circumference correspondingly. For arguments sake, the height of a tire and the circumference are directly proportional…the common factor being Pi.
The rolling circumference is decreased proportionally by the decrease in the radius when under inflated. It’s a dynamic decrease as in appearance, only the bottom appears flat. That is why a car pulls in the direction of a tire with less air pressure…the diameter and rolling circumference are less and tire needs more turns over the same distance then the tire on the other side. Put a smaller diameter tire with the same inflation pressure, it still pulls to that side, in effect, stressing the drive train as well on that axle. That’s why, in a pinch, you can use different tire measurements if it’s possible to equalize their mounting heights by playing with the tire pressures.
Do this if you are the Phantom attempting escape Pigmy poison arrows through jungle in four wheel drive.
Not true - actually the circumference is much less affected by tire pressure than the height is. The belts (often steel) don’t expand and shrink very much at all when the tire is inflated and deflated. That’s why the feds refused the carmakers request to use the ABS sensors as tire pressure monitors - the change in distance covered per revolution is not very sensitive to tire pressure. That’s why were stuck with those expensive, troublesome TPMS sensors inside the tire.
The car pulls in the direction of the deflated tire because of the much higher rolling resistance of the low-pressure tire. That’s why low tire pressures all around decrease gas mileage.
I hear you…you are right with respect to radials which all cars have now and short distance gross measurements. The outer most layer of rubber is forced to compress to conform to the steel belts creating the squirm that generates heat. Is it measurable over short distance…I agree no. But is it significant in circumference difference as a cumulative factor due to differences in tire pressure, for sure. And that difference is enough to induce drive train and handling problems.
And, even tire rack says that different inflation causes a difference in the number of rotations per mile due to the difference in diameters.
I would add that you should never put a part time 4 wheel drive in 4 wheel drive at highway speeds. The same binding that that happens on dry pavement will spin you like a top at expressway speeds if it is slippery. If you are an experienced off-road racer with razor sharp reflexes you might be able to handle it, but then you would probably have more sense than to do it unless you were off-road racing.
Allow me to second what Texases wrote.
Rolling diameter (or circumference) can NOT be measured in the normal manner. The ONLY way to do it is to mark the tire and roll it one revolution and measure the distance traveled on the ground. You can NOT get it with a formula involving PI!
HOWEVER, you can get a good ESTIMATE if you take the actual inflated (and unloaded) diameter and subtract 3%. Loaded radius (referred to in the industry as Static Load Radius) will NOT get you something you can use for rolling diameter. Also, the tire deforms in such a way that the axle is NOT centered relative to the tire - so the overall loaded height doesn’t get you where you want to go.
- and the difference pressure and load makes makes in a tire’s rolling diameter is SMALL, but measureable. That’s how some of the early TPMS systems work. The real reason that was abandoned is that if the tires lose pressure evenly, the system doesn’t know you’ve lost pressure - which is NOT what is intended by these systems.