Differences between LT tires with imperial versus metric sizing?

[Ratbert]

BFG KO3s won't be coming out in 37s (37x12.5R17LT) until sometime in 2025, but that's with an extremely stiff sidewall rating of F. The D rated variant won't be available until sometime in 2026!

LT315/70R17/Ds, however, should be available sometime next year. In theory it's about the same size as my 37" KO2s. I'm thinking that they're basically the same tire, but is that a valid assumption?

See https://dgaddcosprod.blob.core.wind...ents/clz74riy502c701kqq5h7lyvi-v5-bfg-ko3.pdf

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[The Last Cowboy]

The height x width tires were/are called flotation sizes. They existed before metric sizing came to be. The manufactures still market that way because it’s easier for the general public to understand what they are getting, even though often times the same tire company will market a close metric equivalent.

The best thing you can do is choose the size of tire you need with the desired/proper weight rating. Sometimes it’s in a flotation size and other times it’s in a metric size.

Just some of the things I learned working in a tire shop in my younger days.

 

[Ratbert]

Crap, I was thinking LT315/70R17 were basically 37s. They're just a bit over 34s. Shit.

 

[gburchett]

Crap, I was thinking LT315/70R17 were basically 37s. They're just a bit over 34s. Shit.

Yeah that size is a metric 35 tire.

 

[The Last Cowboy]

I don’t think there is a metric equivalent for 37s until you get to 20” wheels. Then you’re looking at load range G at least.

Edit. I found the metric size for 17” wheels. 315/80R 17. Nitto makes a tire in that size, or they used to. Can’t find it now.

 

[azwjowner]

I don’t think there is a metric equivalent for 37s until you get to 20” wheels. Then you’re looking at load range G at least.

Edit. I found the metric size for 17” wheels. 315/80R 17. Nitto makes a tire in that size.

BFG used to make the KM2 in 345/75R16. Now that was an oddball size, but 37 inches.

 

[2nd 392]

Crap, I was thinking LT315/70R17 were basically 37s. They're just a bit over 34s. Shit.

Check tiresize. com for a metric 37/12.50 equivalent. I don’t recall seeing one. I know AT3’s in 35/12.50 are C or E, the same spec tire except D rated is listed 315/70. 37’s are either 12.50’s or 13.50’s, no metric equivalent.

 

[AcesandEights]

315mm = 12.4" * .7 = 8.68 * 2 = 17.36" + 17 = 34.36"
315mm = 12.4" * .7 = 8.68 * 2 = 17.36" + 18 = 35.36"
35 x 12.5 x 17 = ~35 x 12.5 x 17

 

[Ratbert]

Yeah, it looks like I'll either have to go with 37" KO3 Fs or find something else. I'm thinking the F is going to be pretty bad on and off road. I can't imagine that they'll do well when aired down to ~12 PSI.

 

[azwjowner]

Yeah, it looks like I'll either have to go with 37" KO3 Fs or find something else. I'm thinking the F is going to be pretty bad on and off road. I can't imagine that they'll do well when aired down to ~12 PSI.

Find a used set of KO2s to last you one extra year. Or the Toyo Open Country A/T III is a pretty close match to KO2s/KO3s, and it comes in 37x12.5R17 in load E.

 

[Ratbert]

Find a used set of KO2s to last you one extra year. Or the Toyo Open Country A/T III is a pretty close match to KO2s/KO3s, and it comes in 37x12.5R17 in load E.

That's an interesting idea to get used KO2s to make it another couple years. Or just screw it and buy something else.

 

[The Last Cowboy]

Here's the latest Falken AT4W in a 37. It's a load range E, but only 65 PSI max. And not too bad for a 37" radial at 79 lbs a tire.

https://www.tirerack.com/tires/tire...ed Black Letter&partnum=725R7WPAT4W&tab=Sizes

 

[2nd 392]

Toyo 37/12.50/E is 73 lbs. just under 5 lbs heavier than KO2 D’s. Lighter than Cooper D’s, Falkens weight need not be mentioned…..

 

[Gangplank]

Nitto has a few 37s in D

Trail Grappler - MUD

• 37x12.50R17LT D 124Q
• 38x13.50R17LT D 121Q

Ridge Grappler - Hybrid AT

• 37x12.50R17LT D 124Q
• 38x12.50R17LT C 118Q

Recon Grappler - AT

• 37x12.50R17LT D 124R
• 37x13.50R17LT D 125R
  

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