Spare tire question (1 Viewer)
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- #3
s***. I currently have 275/65/18 not 285/65/18. Does that make too much difference?
I think the big issue here is that you want to go with 4 17 inch wheels, but keep your 18 inch spare. That would definitely cause issues with your diff. in case you need the spare.
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- #5
What difference does the wheel size make? Isn't it just the overall diameter of the tire with wheel that matters.?
Huh?
With that new info, IMHO, that’s too much difference for anything other than short distance emergency use. So I think it depends on your use case. If you’re going places you may need to use the spare for long distance highway use, get a same size spare. If you’re just driving local within a few miles of a tire shop, no worry with that spare. By the way, I used the Discount Tire tire size calculator to find the differences. I think anything over a half inch in diameter difference is too much, but others on here will likely disagree.
That's what the OP said in his first post. "If I go with 285/70/17 Is there any harm in keeping my 275/65/18 As a spare..."
Personally, I would never have a spare wheel in a size different than my other 4 wheels in the truck. A slightly different profile on the tire (60x65) might be passable for short distances, but not different size wheels.
those are close enough I wouldn't worry about using it in an emergency/short term situation.
Why wouldn't you run a different size rim as the spare if the overall diameter of the tire is the same as the rest?
Wheel sizes are irrelevant in this scenario. Only the overall diameter of the tire matters. The differentials can't tell the difference between a 275-60-20 versus a 255-85-16 tires. There is a .1" difference between the two and that isn't going to cause any problems.
Yup, only a tenth of an inch difference. I'd be fine with that.
Tire Size Comparison
Tire size comparison the easy way. Use our tire size comparison calculator to compare diameter, width, sidewall, circumference and revolutions per mile.
I beg to differ. I think the drivetrain and diffs will be affected. Even small differences in tire/wheel diameter (from different brands, tread depths, or inflation pressures) can result in a mismatch in revolutions per mile. This places a continuous strain on the drivetrain/diffs if used at higher speeds or a prolonged period of time, especially in vehicles where all four wheels are powered at all times. Again, in an emergency at low speeds and short distances you might be ok, but I would rather not do that in any case if taking about different size wheels since it is an additional component to calculate the overall diameter to the other wheels/tires. That said to each their own.
Assuming all tires are the same size the general rule of thumb that I was given for all wheel drive vehicles that one should not have more than 2/32" difference in tread front to back and none side to side. That is for normal driving and obviously there can easily be +/- 1/32 difference.
When it comes to a spare for short term there can be a larger difference without any long term affect.
IMHO it is best to run five wheels/tires and do a five tire rotation. Most rarely get a flat so the spare is wasted rubber. That is they age out. Further, spares are often neglected, low air or flat (though the LC has TPMS). Further, by regularly dropping the spare, one can lube the mechanism which will rust and freeze in place.
As I say though for short term as spare no real issue but I not sure I would drive a long distance.
When it comes to a spare for short term there can be a larger difference without any long term affect.
IMHO it is best to run five wheels/tires and do a five tire rotation. Most rarely get a flat so the spare is wasted rubber. That is they age out. Further, spares are often neglected, low air or flat (though the LC has TPMS). Further, by regularly dropping the spare, one can lube the mechanism which will rust and freeze in place.
Short term no real issue but tires sizes are nominal. Get two different tires that are nominally the same and do a real measure measurement and one will likely find a difference. Tire Rack does a good job of showing that difference on many tires. If one compounds that with different diameter wheels and tires with different inflation pressures there is likely to be even greater difference between the nominal sizes.
As I say though for short term as spare no real issue but I not sure I would drive a long distance.
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@TheIcemanCometh @MRego In theory, I agree. But in practice, I think it's a non-issue and no long term damage will be done if overall diameters are close. Most folks on Mud aren't going to run three 17" rock warriors and one 20" stock tire for very long. Even if it's a thousand miles at 80mph to get home from the week long trip, the vehicle will be fine. All four wheels have power available but they are not all putting power to the ground. Any amount of turning while driving causes more wear and tear on the drivetrain over 100k miles than running one tire .1" smaller for 2,000 miles.
I do agree that looking up the advertised size on Tire Rack for the model and size in question would be the best way to judge tire size differences. The link I posted is a general reference based on math only, not real world measurements. The OP never gave make and model of tires so it's the easiest way to come close.
I do agree that looking up the advertised size on Tire Rack for the model and size in question would be the best way to judge tire size differences. The link I posted is a general reference based on math only, not real world measurements. The OP never gave make and model of tires so it's the easiest way to come close.
I did this with my wife's Wrangler since the tire is easy to get to and definitely the best option. Now, when buying 4 new tires, the best of the old ones gets mounted to my spare rim. Keeps them relatively fresh and I'm too cheap to buy 5. That, and my spare rim doesn't match the other 4.
gaijin
GOLD Star
It's always rewarding when there is a Toyota document to refer to when answering a question like this - as is evidenced by the diversity of opinions offered so far.
Here is the Toyota document regarding the installation of 17" TRD "Rock Warrior" wheels on a 200 Series Land Cruiser:
17-Inch TRD Alloy Wheel Installation
Of interest is that this technical guide refers to the installation of FOUR 17" wheels on a vehicle that comes standard (OE) with 18" wheels.
So... What about the spare?
On the front page of the guide we find this:
Item 5 refers to a Tire Pressure Door Jamb Label for the Land Cruiser MDC# 00602-60080. Here is a picture of that label:
Note that the 4 mounted tires are the LT285/70R17, but the spare remains the OE P285/60R18.
Apparently, Toyota have no problem with using the OE P285/60R18 tire/wheel combo as a spare should one of the LT285/70R17 tires fail.
To further support this, later in the document, where after work follow-up is explained, we find this:
The important thing to note about this is that "5 OE flat-seat lugnuts" are required to be placed in the jack storage location. And why would those 5 OE lugnuts be required? To mount the OE 18" wheel that is in the spare location.
Although not specifically mentioned in the Toyota document, it is safe to assume that nowhere would Toyota endorse using a tire/wheel combination that has a different overall diameter should be used under any circumstances other than short duration, emergency, preferably low speed, use.
I have 5 identical LT285/70R17 tire/wheel combos and regularly perform a 5-tire rotation, so I do not have this quandary - nor would I, personally, recommend a spare tire with a different overall diameter even though Toyota doesn't seem to have a problem.
TL;DR:
You are probably fine with a 275/65R18 spare when running 285/70R17 tires. Just don't go on any cross-country trips at 100mph with the spare tire mounted - use common sense,
HTH
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- #18
This is great. My wallet thanks you
The math on those two sizes, not real world measurements of brand and model, gives a difference of 1.2 inches in overall diameter. That's more than would have expected Toyota to be okay with. Definitely good information, thanks!
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- #20
This is good. I have a 275/65/18 in the spare which puts it closer to the 285/70/17 than the 285/60/18
