Advice On Boat Trailer Wheel/Tire Upsize

Soooooo, I just bought the family a 32 year old Boston Whaler that may become my first Project Thread on here.  It came with a 32 year old trailer that is all beat to hell  -- Lets just say the 60 mile tow home from Long Island was an adventure.

I've spent a lot of time around car trailers, but small boat trailers are a new world.  I need to replace the dry rotted (date code 2002)  4.80 - 12 tires, and am looking for advice about whether to stay with the current size or upsize to 5.3-12 or 175/80-13.  The difference in diameter is +1.4" for the 5.3, and +3.5" for the 13s.  Pricing seems to be about the same for all 3 options, with some good deals to be had on Am*zon & Redneck Trailer.com

The boat weighs about 1200lbs fully loaded, and the trailer (1988 Shoreland'r) weighs about 150-200lbs I'd guess.  Most of my towing will be 2-3 hour trips on highways, with some hills.  I'm not worried about load rating, just more about towing at highway speeds and taking some strain off of the hubs.   

I am also going to be replacing the toasted, wobbly hubs and moving to new, softer leaf springs, as the ones on the trailer are too much for the weight of the boat, and don't really flex at all. 

Many Thanks for any insight you can share.

Look around for tires first, see what you can find short notice.  My recent trailer came with 5.30-12 tires and I had to order them from Amazon as no one else, even the trailer companies, had unmounted tires alone.

My $0.02

Which Whaler is it?  There are a few other of us Whaler owners on here, I've had either a 13' or a 17' my whole life.   I'm currently restoring the 17' we have owned since 1991.  
 

a trailer is a system, needs to work together.  Axle determines bearing size and hub size which determines bolt pattern which impacts wheel sizes and therefore tire sizes, etc.  

In reply to Sonic :

Thanks, cool, I figured there were some Whaler guys on here!  What 17 are you restoring? I have a feeling this is like going down a new kind of rabit hole. When I started lurking on the Whalercentral and continuouswave message boards a couple of months ago they reminded me an awful lot of this board.

The boat is a 1988 15 Super Sport Limited model,  the one with a fiberglass dual console insert and rear casting platform and factory ski pole, with 70hp Evinrude looper. I remember when these came out; I was 12 years old, and wanted one desperately as an upgrade from my old 14 Sears gamefisher aluminum vee!  Its in pretty good shape. Main needs are new mounting footings for the insert, all 3 thru hulls replaced, and a rewire.

Yes, it interesting to see how the trailer components work together.  This one seems clearly made for a heavier boat, with about 3.5' of extra tongue length.  It has what looks to be a 2000lb stick axle, and 3 leaf leafsprings.  As it is, when the trailer hits a bump the springs don't give at all, in terms of absorbing any impact, so the trailer just bounces around, rattling on the ball/coupler. (This is a new, scary experience for me!)

I'd go with the tallest diameter you can fit on that hub if you are going to be on the highway much. You'll probably have to rework the fenders but to me its worth it. Normally the drawback to taller tires is tire to fender to boat clearance issues, plus the fact you have to get the trailer deeper to launch because of increased height. With 3.5' of extra tongue that wont be a problem. 

We tow a 15', 1200lb boat 4 hours each way multiple times a year. I upgraded to a used roller trailer meant for a 20' boat. Overkill?  Absolutely but it tows great and is solid as a rock. Plus the extra length keeps my tires dry launching on shallow ramps. See if you can tighten your hitch on the trailer to reduce rattle  and if the draw bar moves on the receiver hitch get an anti-rattle kit for it. It will help your sanity.

If it doesn't make the boat sit too high, I would go with the 13 inch tires.  Otherwise go with the 5.3-12.  

It might look made for a heavier boat, but you gotta consider how much crap you're going to put in the boat when you tow it, too.

Fuel is heavy!

Fuel = 6lbs./gallon.

I buy small wheels all the time for golf carts, these are 8-10 inch.  They are so small that even mower & farm equipment shops won't touch them.  Not sure if 12" are on that list.  
 

My trailer has 12" 5 X 5.5" rims, I swapped them out for 15" Ford LTD rims.  It rides better.  Buying the little guys, Wal-Mart offers the best deal.  12" from a place like Tractor Supply or a mower shop is $60 - $72, Wally World is $37.

You know we need pictures right?

Dan

(watch the Build forum soon)

I too would go with larger tyres for highway use. The slower you can spin those bearings, the longer they will last. 

175/80-13.....& galvalnized rims if you can find them....one less thing to worry about rusting out. McClain trailer here in the Houston Tx area sells them   

Bigger has a ton of benefits.

Boat trailer axles are often limited by wee little bearings.  You likely have 1" or 1-3/8" bearings, or a combination of both.  On my little 12' boat trailer with 1" bearings, I usually repack them every year, and I don't ever expect them to last more than a few years.  This is primarily because of the tiny donut 4.80-8 tires.  They make those little bearings spin fast.

Small tires also have a lot more forces at work.  Because they spin fast, and because their radius is so much smaller, the desire for it to fly apart is much higher.  They're constructed to handle it, but when you have the combination of that high moment of inertia, the small circumference taking abuse from the tiniest pothole, and the fast speeds they spin, they tend to not last as long.

Another big benefit is the larger circumference is that the boat will take a lot less abuse from bumps.

I finally upgraded my 15' fiberglass tri hull's trailer to 5.30-12s up from 5.70-8s and it's so much nicer to tow.  I gained a good 4" of diameter and it made all the difference.

Thanks Everyone for the tips!  Went with the 13s as they will justbarely clear the welded-on fenders.  The spring/axle mounting is overslung, so I can add a spacer if needed.

I think I am going to start a build thread, but I'm limiting non-work online time to an hour a day so updates will be slow.  In the meantime, here's a pic of the boat the day I brought her home:

That's a worthy project.  The 15 footers aren't as common as the 13 and 17 footers and the 15 footer is a huge improvement ride wise over the 13.  With the right set up and a healthy 70 HP 2 stroke they've been known to get to 43-45 mph.  That's scooting for a 15 foot open boat. 

You've already dealt with the trailer tires, I have a 17 Montauk with a 90 HP Evinrude on it and have had no issues with 150 mile trips with the 12 inch tires.    After you rebuild the hubs get some "bearing buddies" or similar spring loaded grease cups, they work really well at keeping water out of the hubs.   If you bought new rims for the 13" tires, consider keeping one of the 12" for a spare.  

Hi All - Thanks again for all the trailer advice! Just a little bit ago I finally started the build thread.  Linky here