Tire size question

computersoc · Oct 1, 2017

My door says my 2001 Ranger XLT 2.5L RWD takes P225/70R15SL. My rears have 215 75 15 and my fronts are 215 70 15. I need new front tires and will order them online. Should I just get the proper size or can I get the same size as my rears since they're $10 cheaper per tire? My speedometer is accurate.

I also notice my rears lose 10 psi a month. Both evenly. My fronts lose 1 psi a month. Is this coincidence or is it because of tire size? They don't have a nail in them but the shop that put them on was sort of cut rate, and I know they didn't put new valve stems on.

pjtoledo · Oct 1, 2017

Rangers tolerate a wide selection of tire sizes. just keep it within sight of the factory size and preferably all 4 the same size. if you have to mix 'n match sizes make the rears larger. 2 wheel drive only of course.
the Tire Rack (tirerack.com) has specs on lots of brands so you can see the actual tire dimensions and recommended rim widths.
all 4 on 15" x 6" steel wheels now?
steel usually holds air better than aluminium in my experiences, especially once they have aged.

computersoc · Oct 1, 2017

They're aluminums. I have snow tires on my steels. Those don't seem as bad.

wildbill23c · Oct 3, 2017

Since its a 2WD having the exact same tire sizes on the front and rear isn't as important. So, if you are wanting to replace the 2 front tires, you may as well get them in the same size that the other 2 are. Or, replace them all at the same time with the size that's on the door label. Either way will be fine. Now if it were a 4WD you'd want the same size tires all the way around, but 2WD isn't really going to make a difference, maybe unless you rotate tires then it would possibly make a difference.

computersoc · Oct 3, 2017

Aren't I still supposed to rotate the tires on 2WD?

alwaysFlOoReD · Oct 3, 2017

computersoc said:
Aren't I still supposed to rotate the tires on 2WD?

Yes.

Buy the same size as the rears. Ideally all the tires should have the same amount of wear [tread depth]. I've never lived in an ideal world and do what I have to.

4x4junkie · Oct 3, 2017

Agreed. 215/75R15s should be fine (they are within about 0.3" of the original size, not enough to change the speedo reading or engine RPM significantly).

On the subject of wheel composition and holding air, my experience seems just the opposite. My BII (has steel wheels) seems to lose about 1 PSI a month, whereas my Ranger (has aluminum) loses maybe 1 PSI every 3-4 months).

I suspect different tire brands are what have different rates of air loss... I seem to recall the loss rate did go down a good bit when I went from BFGs some time ago to a set of Goodyears MT/Rs, and then it went back up again when I went back to a set of BFGs on the BII. The Toyo M/Ts I have on my Ranger now also seem to be pretty good about not losing much air. I suspect it's from how much the air is able to permeate through the tire rubber.

don4331 · Oct 3, 2017

computersoc:

New valve stems every time is over rated. If they didn't damage them changing tire and they were in good shape before, they don't really need to be changed.

Corrosion on the rim is why I have leaks. Chrome flaking of aluminum is worst - I've had a set that wouldn't hold air overnight. Steel rims are better - I can clean the rust off and then they are good until oxidation makes its inevitable progress.

4x4junkie:

Are you using air or N^2?

I've never compared between tire brands.

pjtoledo · Oct 3, 2017

4x4junkie said:
Agreed. 215/75R15s should be fine (they are within about 0.3" of the original size, not enough to change the speedo reading or engine RPM significantly).

On the subject of wheel composition and holding air, my experience seems just the opposite. My BII (has steel wheels) seems to lose about 1 PSI a month, whereas my Ranger (has aluminum) loses maybe 1 PSI every 3-4 months).

I suspect different tire brands are what have different rates of air loss... I seem to recall the loss rate did go down a good bit when I went from BFGs some time ago to a set of Goodyears MT/Rs, and then it went back up again when I went back to a set of BFGs on the BII. The Toyo M/Ts I have on my Ranger now also seem to be pretty good about not losing much air. I suspect it's from how much the air is able to permeate through the tire rubber.

you're in corrosion free California, I'm not surprised.
here in the great rust belt, when salt hits aluminum the aluminum turns into a white powder and blows away in the wind. the bead area is notorious for this as the side wall constantly flexes against the lip. many aluminum wheels have craters in them where the finish has been chipped.

JohnnyO · Oct 5, 2017

215/75-15 are very close to the same diameter as the OE 225/70-15 size, just a little bit narrower. If the rear tires have only a year or so left on them then I would get 225/70's now, put them on the back, and the 215's on the front. Then get 225/70's when the 215/75's wear out. If the 215/75's are pretty new then I would get another pair in that size.

4x4junkie · Oct 5, 2017

don4331 said:
4x4junkie:

Are you using air or N^2?

Plain ol' air from our atmosphere (it is about 78% N2 though :icon_twisted:

)
Nitrogen inflation wouldn't be practical for me since I usually air down for off road.

pjtoledo said:
you're in corrosion free California, I'm not surprised.
here in the great rust belt, when salt hits aluminum the aluminum turns into a white powder and blows away in the wind. the bead area is notorious for this as the side wall constantly flexes against the lip. many aluminum wheels have craters in them where the finish has been chipped.

Ah ok, that would make more sense. Yeah we don't see rust & corrosion issues here real often, though it's not entirely unheard of, particularly next to the coast.

Tire size question

computersoc

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pjtoledo

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computersoc

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wildbill23c

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computersoc

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alwaysFlOoReD

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4x4junkie

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