1999 Montero Wheel/Tire Questions

[speedtre]

First off I did a search but did not find an answer to my questions os, here goes.

I'm getting ready to buy a 1999 Montero in great condition, only thing it needs is tires. This is where it gets odd in my research on tires for the Montero.

Near as I can tell, it comes with 15x6 wheels with 265/70/15 tires on it. Every replacement tire I find in that size, the manufacturer recommends at least a 7 inch rim. This is also true of 31x10.5 tires.

Am I wrong on the wheel size of the Montero who has conventional wisdom changed on what size tires should go on what sized rims in the past 11 years?

I assume if it's OK to put 265/70/15s on 6 inch rims it's also ok to put 265/75/15s on since they are no wider and people are putting 31x10.5s on the stock rims (which is a little wider than 265/70/15s)....right?

I just would prefer not to replace the rims right now for budgetary purposes but I would like the largest possible tire that is safe on those rims.

One other question, if I do go with a larger tire (265/75 or 31s) do I have to replace the spare? It's a 265/70/15 in perfect shape, so I'm hoping if I had to use it in a temporary emergency situation it would not be a problem being a slightly smaller size....is that right or would I be risking causing some damage to the drive-line? Again, just trying to save a little cash.

In my research I came across a great tire size comparison chart for those interested.

http://www.1010tires.com/TireSizeCalculator.asp

 

[Silverwulf]

If changing from the stock 265 70 15 tires to 33 12.5 15 tires , how off will the speedo be?

 

[off-roader]

If changing from the stock 265 70 15 tires to 33 12.5 15 tires , how off will the speedo be?

Simple ratio problem actually (makes you wish you paid attention in math right?). ;^)

33/29.6=1.114-1.0= .114 or 11.4% bigger tire which means 11.4% speed increase in speed over what your speedo says.:ylsmoke:

 

[speedtre]

You can use the link in my first post and plug in the tire sizes and it will tell you the exact difference. According to that site the difference
is 9.865%. Evidently 33s are actually a little smaller than 33...according to that site anyway. All tires vary a little depending on brand.



Now does anybody have any answers to my questions?!?

 

[off-roader]

Cant answer your first question about safely mounting that tire. I can give you anecdotal evidence that it may be ok...

I've run both 33x12.5x15 MT KM & 35x12.5x15 MT KM2 BFG tires on a 15x8 rim. BFG recommends a minimum 8.5" rim for either tire yet the tire shop (america's tire/discount tire) has never had an issue mounting them and they do normally tell you if it would be unsafe. I've run these two setups for well over 50k (closer to over 100k actually).

Have you asked a shop their thoughts?

As for the spare, my feeling is... if you only need to change out a front end flat, you'll be ok but a rear flat could possibily lead to diff gear issues if driven for any extended period... (i.e. you may be able to drive it a few miles to an exit or a tire repair shop but not further).

HTH.

 

[tdesanto]

I would like to help, but I don't remember the size of the OEM wheels for the '99.

I would like, though, to suggest that you might find better luck with a 33 x 10.5" tire instead of the 33 x 12.5. The width would be very close to stock and would likely work on your wheels and give you the height that you want.

As for the spare, I think you should do it.

1) I think (I could be wrong) it puts too much strain or builds unnecessary heat in your diff if you use different sized tires on the same axle. Maybe manual hubs in the front (I think that's an option for the gen 2/2.5 trucks) might help you with this situation if you put the smaller size on the front axle and had the manual hubs unlocked.
2) You can rotate your spare. With the spare being so accessible, don't think of the spare costing you money as much as it's going to help your new set of tires last longer.

I'm buying a new set in a couple hours and even though I'm not changing sizes, I'm still going to replace the spare. That way I've got an excellent tire to put into service whenever I need to and I can extend the life of my new set by 20% by rotating the spare in at each rotation.

 

[RttH]

I'm too lazy to go calculate anything but according to my GPS and any speed trap signs, I am going 72 mph when my speedo says 65. At slower speeds like 40 I am really going 45 (according to GPS). I am running BFG KM2's 33x10.5x15 on 15x7 rims. And I do rotate my spare with the other tires as it does add to the longevity of them all. I rotate often too...every 4 months.

Having run 32x 11.5 AT and MT and now 33 x 10.5, I am sold on skinnys. It just "feels" livelier and gas mileage is good.

 

[speedtre]

Thanks for all the great info everyone!

I'm definitely not getting 12.5...I just don't need them for my uses, they would be overkill.

Roger, do you run those 33x10.5 on the stock rims?

 

[RttH]

Yes and no problems so far. Here are BFG AT 32x 11.5 and one on driveway with 33x10.5 KM2's

 

[DavidG]

I thought 15x7 was the width for the factory alloys. 32x11.50 or 33x10.50 and be done with it. If you are thinking of changing wheels, the factory FJC steel wheels in 17x7.5 will work once you clearance the centering tabs. This is an inexpensive wheel alternative. I run 255/75-17 (roughly 32x10) on my 97 Montero SR.

Just noticed you are in Atlanta. We should get together sometime...

 

[PajEvo]

Another vote for skinnies. I ran 33x1050 BFG ats on my last genII (JDM 2 door) on factory 7's, and now I'm running 33x1050 BFG KM2's on factory 7s on my jdm 4 door diesel. My truck came with 490s in the diffs though, and I think that's what I'd be putting in there if they weren't there already.

As for spare, I always match it. As stated above, you would really need to swap it to the front if you had a rear blowout. No fun...

Interesting what happens to your speedo though. My speedo is under stock on my factory sized snow tires, and almost dead on, sitting on 33s. Check it against your gps before and after upsizing. You may be surprised!

 

[cocovi]

just "feels" livelier and gas mileage is good.

 

[biff]

for reference, I am running 32x11.5

 

[speedtre]

for reference, I am running 32x11.5

Very nice, is that stock suspension, with no lift at all?

 

[madmonty]

I joined this site a couple of weeks ago, I own a 2000 Montero Sport and enjoy it very much, it's a great vehicle and I've owned many different makes of 4X4's.
I've checked out lots of 4X4 sites over the past few years and have to say: This site contains a wealth of valuble info and from what I've read so far (both questions and replies) you all seem very knowledgable and know what you're talking about.
That tire size calculator link is great, thanks for posting that! :smiley_drive:

"KEEP ALL FOUR WHEELS SPINNIN AND YOU'LL KEEP WINNIN"!