What Pressure 255 KM2’s ?

110 on 7" disco 1 alloy rims (255/85 KM2's) quoted in psi

bituman F36-38 R38-40
high speed dirt/gravel F26-28 R30-32
low speed dirt/gravel (high range) F20-22 R22-24
low range off road 16-18 F&R depending on terrain but have comfortably run 14 on tracks like Mt Airley and Mt Walker.
sand i've been down to 12 without rolling a bead but was very weary.

i'm yet to find a happy medium on bitumen. At lower psi (low to mid 30's) the tyres tend to roll on the rim making corners interesting. At 40 psi it corners predictable enough but is a harsh ride and the rear chatters if there is no weight.

Not sure if others experience the same but my KM2's seem to keep form except when there is considerable pressure on a point on the tyre (ie driving over a rock) even at 15psi. Stated another way they don't seem to bag or to have a long footprint when driving at those low pressures. When you look at my photos when off-road you could swear i'm running bitumen pressure by the look of the tyre wall. I've seen a set of 285/75 KM2's at higher pressure bag more than mine.

just curious if I'm an odd one out or it's a KM2 characteristic.

cheers MLD

I run mine on 6.5" rims. For me they seem to bag an awefull lot. I often have rub well past the side brightest and up the side wall. You could alway measure foot pad length with two sticks at road pressure, then dirt pressures and so on. But yes some tyres don't seem to bag much compared others. Personally I'd prefere more side wall stiffness with less side wall bag. All the grip is in tread length but one contradicts the other.

I tent to run about the same as David, a couple of psi less in the front.

Also, I'm seeing a lot of people running this size & model on 6.5" rims. I'm nearly certain the BFGoodrich site details that a 7" rim is the min width for these and a max rim of 8.5", its a year or two since I researched into rim sizes for mine, but I seem to recall I got 7" cos that was the smallest and I could still run 235x85 R16s on a 7" if I wanted also, which I couldn't on an 8".

HTH
J

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Quote:

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Originally Posted by Yorkshire_Jon

I tent to run about the same as David, a couple of psi less in the front.

Also, I'm seeing a lot of people running this size & model on 6.5" rims. I'm nearly certain the BFGoodrich site details that a 7" rim is the min width for these and a max rim of 8.5", its a year or two since I researched into rim sizes for mine, but I seem to recall I got 7" cos that was the smallest and I could still run 235x85 R16s on a 7" if I wanted also, which I couldn't on an 8".

HTH
J

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Nope, BFG have always listed 6.5"-8.0" for the 255/85 with the measuring rim width being 7" ;)

Maxxis list 7.5"-8.5" or something silly like that and it's a typo that keeps being repeated in each subsequent catalogue.

[edit] Here's an '03 and I think current (actually from '09) tyre size chart for BFG MT's below

Hmm, it doesn't look like the forum will let me post two pdf's in the one post...

Quote:

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Originally Posted by Yorkshire_Jon

I tent to run about the same as David, a couple of psi less in the front.

Also, I'm seeing a lot of people running this size & model on 6.5" rims. I'm nearly certain the BFGoodrich site details that a 7" rim is the min width for these and a max rim of 8.5", its a year or two since I researched into rim sizes for mine, but I seem to recall I got 7" cos that was the smallest and I could still run 235x85 R16s on a 7" if I wanted also, which I couldn't on an 8".

HTH
J

Sent using Forum Runner

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tire rack US quote 6.5", I havent checked again and could be wrong but I think BFG Aus say 7". I can certainly vouch for the suckers stay on a 6.5" rims in all conditions and psi variants. I have not been below 15psi however.