2018 Subaru XV - needs urgent tire replacement

[dr. d]

Then why does the manual say it accepts both?



Do you mean "one MAY CHANGE tyre diameter without changing rim size" instead? I was just thinking out loud if I don't find the exact 18" tire size, at least I have the option to go 17". But I don't know what the disadvantages are if I were to downgrade.

the tyre diameter will literally dictate the rim diameter size, and vice versa.
a tyre diameter of 17 inches will only fit into a wheel diameter of 17, and a rim diameter of 18 will fit only tyres with an 18 inch diameter.
tyre diameter refers to the size of the empty space in the tyre. rim diameter refers to the distance between two opposite edges of the rim. or something like that.

tyre circumference figures directly into the car's dashboard's distance- and speed-measuring instruments.
tyre charts will show tyre changes from one size to another, with the corresponding changes in tyre circumference.
the objective of these tyre charts, is to ensure that changes in tyre circumference are kept to a minimum, when changing tyre diameters.
the manual knows about the above, hence its statement that it can accept both.

note that another potential problem with tyre size changing, is that sometimes the bigger (fatter) tyre might rub onto the car's metal under certain maneuvers.
best to ask the knowledgeables first, before purchasing yon tyres.

[kevindd992002]

the tyre diameter will literally dictate the rim diameter size, and vice versa.
a tyre diameter of 17 inches will only fit into a wheel diameter of 17, and a rim diameter of 18 will fit only tyres with an 18 inch diameter.
tyre diameter refers to the size of the empty space in the tyre. rim diameter refers to the distance between two opposite edges of the rim. or something like that.

tyre circumference figures directly into the car's dashboard's distance- and speed-measuring instruments.
tyre charts will show tyre changes from one size to another, with the corresponding changes in tyre circumference.
the objective of these tyre charts, is to ensure that changes in tyre circumference are kept to a minimum, when changing tyre diameters.
the manual knows about the above, hence its statement that it can accept both.

note that another potential problem with tyre size changing, is that sometimes the bigger (fatter) tyre might rub onto the car's metal under certain maneuvers.
best to ask the knowledgeables first, before purchasing yon tyres.

Right. So does that mean that the 225/60R17, regardless of it being accepted by the car (based on the manual), I still need to change the rim/wheel with one that has a 17" diameter?

[dr. d]

Right. So does that mean that the 225/60R17, regardless of it being accepted by the car (based on the manual), I still need to change the rim/wheel with one that has a 17" diameter?

you are correct, po.
a 17 inch tyre simply won't fit onto an 18 inch rim.

"being accepted by the car" means that the tyre will function properly when installed onto the car.
but one has to get the proper-size 17 inch rims, as the 17 inch tyres won't fit onto the 18 inch rims.

also!
aside from rim diameter, one also has to consider other rim features like offset and others.

think of the tyre-and-rim combo as one's ring-and-finger.
there are many sizes of rings, because there are many sizes of finger diameters.
for proper and comfortable fit, the ring (tyre) must be not too tight, nor too loose, around the finger (rim).

[kevindd992002]

you are correct, po.
a 17 inch tyre simply won't fit onto an 18 inch rim.

"being accepted by the car" means that the tyre will function properly when installed onto the car.
but one has to get the proper-size 17 inch rims, as the 17 inch tyres won't fit onto the 18 inch rims.

also!
aside from rim diameter, one also has to consider other rim features like offset and others.

think of the tyre-and-rim combo as one's ring-and-finger.
there are many sizes of rings, because there are many sizes of finger diameters.
for proper and comfortable fit, the ring (tyre) must be not too tight, nor too loose, around the finger (rim).

Ok, got it. Then I'll stick with the 18" tires to make everything simple, lol. Do you have any personal recommendations for a midrange brand/model of tires? The Otani's would've been perfect if they have the exact 225/55R18 size I need.

[dr. d]

Ok, got it. Then I'll stick with the 18" tires to make everything simple, lol. Do you have any personal recommendations for a midrange brand/model of tires? The Otani's would've been perfect if they have the exact 225/55R18 size I need.

alas!
i am but a humble yokohama fan of factory-spec innova tyres.
cheap, available, and reliable.

[kevindd992002]

Any comments on using tires with a different section width and aspect ratio compared to stock? Based on my research, +- 3% on the overall diameter (and therefore circumference too) is a good rule of thumb for modern cars. Based on this calculator, this is what you get for a 225/55R18 stock tire size:

[yapoy86]

you also need to consider the increase in width of the tires vs the rims can accommodate.. it will bulge on the rims.. aka buntis look..

yokohama is a good option for daily drive.. unless you're sporty sporty and inclined to do some track time

[Egan101]

225/55/18 yung stock tires ng XT ko. No issue at all putting 235/55/18 on it now.


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[yapoy86]

275/45/18 yata yung lumabas dun sa calculator nya

[kevindd992002]

Yeah, I know hindi kasya ang 275mm. I just sent the calculator results as a reference.

Here are the available 18" size variants for the Otani KC2000's though: KC2000 | Otani Tyres

My stock tires have a load index and speed rating of 98V. So if I isolate the 18" tires from that list that are at or above the same 99V rating as my stock tire's rating, I end up with these sizes:

235/55ZR18 (104W, 1.56% diameter variance)
235/50ZR18 (101W, -1.77% diameter variance)
235/45ZR18 (98W, -5.11% diameter variance)
245/45ZR18 (100Y, -3.83% diameter variance)

Further removing the ones with more than 3% diameter variance, we're left with 235/55 and 235/50 which is what Egan101 recommended in the first place. The difference in price between the two (per tire) is just around P200 so that's insignificant.

Otani vs. Yokohama? Which is generally better? May specific model ba kayong marerecommend for Yokohama?