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Tires/Tire Conversion (possibly out of date tire)


I have a trailer tire that I need replaced and I can't seem to find it anywhere, it is a 6.70-15LT Load Range C Tubeless, 6 ply rating, 4 nylon tread plies, 4 nylon sidewall plies and the brand is Mohawk Ult1m1ler. Can this size be converted into a more common size i.e. ST225/75D-15" like I see most tires? I've been told it's a hard tire to find so if I can match it up to a commonly used tire that would be great.


Over the years the sizing system has changed.  While there won't be a direct replacement, there will likely be something that will work.

A 6.70-15LT Load Range C has a diameter of 28.4", a width of 7.5" on a 5" rim, with an allowable rim width range of 4 1/2" to 6" and a load carrying capacity of 1520# @ 50 psi (single).

An ST205/75D15 LR C has a diameter of 27.1", a width of 8.0" on a 5 1/2" rim (7.8" on a 5" rim) with an allowable rim width of range of 5" to 6 1/2", and a load carrying capacity of 1820# @ 50 psi.

That looks like that works.  


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Barry Smith


I have over 30 years experience in the design, manufacturing, and testing of tires. I have served as the technical advisor to the "800" number. I have authored or co-authored many publications - usually without credit. I can answer almost any technical question, but please don`t ask me to compare brands. I probably have prejudices because of my work experience.


Member SAE (Society of Automotive Engineers) Member Tire Society (Tire Technical Organization) SCCA Regional Competiton License holder Authored many training manuals on tires, their care and use.

SAE (Society of Automotive Engineers) SCCA (Sports Car Club of America) Tire Society

You may want to visit my web site:

I am a graduate of the University of Dayton, Dayton, OH - BME, 1971 I attended graduate school at the University of Akron - but did not complete my PhD - something I regret.

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