Tire size question

Joined
Oct 3, 2008
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4,639
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Kuwait
Friend of mine has a 3-door version of my Montero/Pajero (same model year), which comes with 15 inch alloy wheels. I'm helping him select a decent tire, but it seems to be difficult to find a decent one in the required size - 31 x 10.5-15 6PR (Load Range C) LT. The speed ratings are fairly low, and when you find one with a reasonable speed rating, the price sky rockets. The OEM Yokohama Super Digger tires are available, but at $160 a piece there are better alternatives IMO. The same can be said about temperature, treadwear and traction ratings - most are B at best. Mine comes with 265/70-16 112H tires from the factory, so they are much easier to source than his as far as specs are concerned. Having checked the USDM version of the vehicle, it comes with exactly the same wheels but the tires are 265/70-15 110H. My question is, would it be appropriate to fit these over the specified tires? Would it be necessary to recalibrate the speedometer or anything like that if these are fitted? It's just that these are better priced, and are better spec'd for his usage. Thanks!
 
Joined
Feb 22, 2003
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Somewhere in the US
According to Tire Guides, the US versions of the Mitsubishi Montero came with a variety of tire sizes - and even in 15", there are several. So the first step is to check the vehicle placard to be sure. If it says a 31x10.50R15LT LR C was the original tire size, does it also say the inflation pressure should be psi 29 front / 40 rear? If so, then that indicates a load carrying capacity of ..... uh ...... well, the chart doesn't go all the way down to 29 psi, but if I interprolate, I get 1549# front / 1945# rear. Other US versions on the Montero came with P235/75R15's - and to get the same load carrying capacity, that tire size would need ...... ah .... again the chart doesn't go that low, but if interprolate I get 24 psi front / 39 psi. (This means the tire has to be an Extra Load) This is at odds to another US versions of the Montero with the same GVW that used a P235/75R15 and the placard says 26 / 35. OK, so a little research is in order. PLUS, I checked on Tire Rack and I see many very reasonably priced tires in a 31X10.50R15LT. AND NO UTQG ratings. Tires in this size are not required to have UTQG ratings, so many manufacturers do not test these sizes. Given what I know about tire sizing, these types of tires should not be compared to tires in P metric sizing for UTQG ratings. And given that the Yokohama Super Digger is an OE tire, which probably means it doesn't wear very well, but gives good fuel economy (and you really need that in Kuwait?), I don't think this would be a good choice.
 

Falcon_LS

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Joined
Oct 3, 2008
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4,639
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Kuwait
Many thanks for the responses! According to the placard, the tire pressures are 29 PSI front and 40 rear, and 31x10.5-15 is the original tire size. This was the OEM size for Montero's coming with 15" wheels in the Middle East, whilst the ones with 16" wheels had a 265/70-16 tire size. Thanks for pointing out the bit about these tires having no UTQG ratings! That had me rather confused. Having done a bit of research, the Pirelli Scorpion ATR is looking rather attractive, as is the Kumho Road Venture KL61 and Firestone Destination LE. I've got Scorpion STRs on my Montero (265/70-16), which I'm very pleased with...but they don't come in the appropriate size for this application, unfortunately. Although given the 15 MPG fuel economy rating for this truck, I would say decent fuel economy is important! But those Yokohama Super Diggers are quite expensive for what they are. The Scorpion ATR is quite a bit cheaper, and a better tire.
 
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