Tire size for 2.375 " axle ?

[sailorman]

Here 's my dilemma . I 've been renovating a 1973 camper trailer ( many previous owners ) . I replaced tires with same size that were on it when I got it . I noticed today that the axle dia. measures approx . 2.37 " . my understanding that this dia . is usually a 3500 # axle . Tongue marking says 350 lbs. max . Tires are 175/80 R 13 rated 1360 lbs yielding total rating of 2720 lbs. Don 't I need tires rated to at least 1750 lbs . I suspect at some time the original tires were replaced with the wrong size ( cheap owner ) .

I think the rims are original and are 13 " 4 holes using lug bolts. Original brake drums appear to be 10 " . Brake backing plates and guts need to be replaced ( wires were cut by someone ) .

The camper ( Go-Tag-Along ) is long out of production and practically no info . is available on the net .

What size tire do ya think was most likely original for this set up ?

 

[Diamondpilot]

Does it really matter? How much does this camper weigh? If its under the load limit for the tires then just use what you have. If you need to step up I would go with 14" and some C rated 6 ply 205/75/14 Radials. This will give you the full 3,500# limit but my feeling is it will be hard to find that for a 4 lug wheel.

Chris

 

[sailorman]

Does it really matter? How much does this camper weigh? If its under the load limit for the tires then just use what you have. If you need to step up I would go with 14" and some C rated 6 ply 205/75/15 Radials. This will give you the full 3,500# limit but my feeling is it will be hard to find that for a 4 lug wheel.

Chris

Chris, thanks for response . One of the problems is I don 't know the weight and have no access to public scales .

I 'm a bit confused though - 14" and some C rated 6 ply 205/75/15 Radials . Isn 't that a 14" rim with a 15 " tire ? Or am I miss-reading .

 

[Diamondpilot]

You are right. I meant to say 205/75/14. Its a typo on my part. I will fix it. I still think the issue will be finding 14" wheels with 4 lug in the right bolt pattern.

Chris

 

[sailorman]

You are right. I meant to say 205/75/14. Its a typo on my part. I will fix it. I still think the issue will be finding 14" wheels with 4 lug in the right bolt pattern.

Chris

I agree about 4 lugs . Probably impossible . I hate havin ' to buy new drums and tryin ' to match them with axle spindles along with new rims and tires . I totally lack knowledge about axle spindles . Hope I can get a little money out of the 3 I have ( like new ) .

 

[Diamondpilot]

I find it hard to believe you do not have access to a scale. Every town around here has one somewhere. Recycling center, grain elevator, truck stop, gravel pit, ect. I slip the guy a $5 bill at my local gravel pit and he lets me weight whatever I want.

I just take the truck with 3/4 tank of fuel and just me in it. I then jot down that weight. I run home, 1.5 miles for me, and get the trailer and go back across and do the math.

If you really do not have one near you then you can do something I did in H.S. Physics class. Take a few pieces of paper and make a grid of 1"x1" lines on the paper. Now roll the trailers tires on this paper and trace as closely as you can the contact patch of the tires. Now take the tire pressure for each tire and write it down. Say its 30 PSI on the left and 31 PSI on the right. You need to be accurate here. Now roll the trailer off the paper and do some estimating. You need to estimate as closely as possible how many square inches your contact patch is for each tire. Say its 40 SQ IN for the left and 39 SQ IN for the right. Now do some math.

Left tire. 40 SQ IN TIMES 30 PSI. 40X30=1200#
Right tire. 39 SQ IN TIMES 31 PSI. 39x31=1209#

This tells you your axle load is 2409# (1200+1209=2409#)

Now use a bath scale to measure the tongue weight using this method and this will give you the weight.

Tongue Weight

When I have done this I have been within 5%. Pretty darn close.

Chris

 

[sailorman]

Chris ,
My scale situation is weird indeed . There is one trash dump scale kinda close, but the ramp up/down is so steep I think the trailer rear will drag badly on concrete .

I 've done the Physics thing once, but couldn 't convince myself that I was accurate even though I taught high school physics for many years lol .

Think I 'll do it again several times and see if I get consistent results . I just can 't believe a trailer would be built with a 3500 " axle, 350 # tongue weight, and OEM tires rated at 2720 # total .

Nothin ' like a trailer tire blowout on a trip knowing your new spare is the same size and blow also .

Thanks for the help and please let me know if ya have any other thoughts in the matter .