Boler tire size?

[Cory K]

I just purchased a 1970'ish 13 ft boler. The tires on it now are 185/80R 13. The spare is a 155/80R 13. I am guessing the spare was once on the trailer b/c it is well used. The 185s on the trailer now seem big and leave little room in the wheel well. It does not help that the axel is worn making the trailer ride a bit low. Any suggestions re: the size of tire that I should install?

[Des Nolan]

I just purchased a 1970'ish 13 ft boler. The tires on it now are 185/80R 13. The spare is a 155/80R 13. I am guessing the spare was once on the trailer b/c it is well used. The 185s on the trailer now seem big and leave little room in the wheel well. It does not help that the axel is worn making the trailer ride a bit low. Any suggestions re: the size of tire that I should install?

Hi,

There are discussions on this forum on the virtues of radials tires vs whatever you call non-radials. The original papers for our '77 boler, however, specify "600 x 13". My tire specialist recommended the modern equivalent as A78 - 13 S.T. which is specifically a trailer tire -- firmer sidewalls, etc. etc. With many kilometers behind us, we have nad no problems.

Des

[Cory K]

Thanks for the info Des - very helpful.

[Benny K]

On my 13' I run the 155/80 R 13's....auto tires and I keep them at about 36 psi and have had no problems although they look kinda skinny under the trailer...also the trailer rides real smooth behind the truck.....Benny

[Bill F.]

I just purchased a 1970'ish 13 ft boler. The tires on it now are 185/80R 13. The spare is a 155/80R 13. I am guessing the spare was once on the trailer b/c it is well used. The 185s on the trailer now seem big and leave little room in the wheel well. It does not help that the axel is worn making the trailer ride a bit low. Any suggestions re: the size of tire that I should install?

The most common dedicated trailer tire size for these 13' fiberglass trailers is ST175/80R13 which almost any tire shop can order for next day delivery. I havn't found anyone who carries them as a stock item except occasionally Princess Auto in Canada. They currently have them on sale with white spoked rims for Cdn$109.95 ea. Since it can be difficult finding a replacement immediately a good spare is reccomended. These ST(Special Trailer) tires have a heavier sidewall and usually a higher load range than P(Passenger) tires, and typically are inflated to 50p.s.i. as opposed to 30-35p.s.i. with passenger tires. I think the original 78 series tires that were used on the Bolers were just passenger tires but now that technology has made ST's availlable why not take advantage of them.
Bill

[Brian B-P]

That originally specified "6.00x13" would be six inches wide, or almost 155 mm, so it would be roughly a 155/xx-13, where xx is an aspect ratio of 78 or more; the spare is likely a near match for the original size. An A78-13 would be about the same size, while a B78-13 is closer to the 175/80-13 which Bill mentioned. The 185/80R13 is definitely bigger than stock.

I think bigger than stock is appropriate, just as modern cars use much wider tires and larger diameter wheels than the cars of the 1970's to suit modern driving conditions and expectations, and people improving 1970's cars (not stock restorations) put bigger tires on them.

The "ST" designation before a modern size (e.g. ST175/80R13) or on the end of a "traditional" size (e.g. B78-13ST) means Special Trailer; it's that designation, not the size, that indicates that a particular tire is specifically for trailers. I really don't think ST tires have any new technology; instead, it is the Passenger (P) tires that have advanced. There are lots of discussions in this forum of ST versus P (and versus LT and commercial) types of tires; the subject of sizing (including the use of lower aspect ratios) appears in the same topics.