Can I upgrade to 14" tires from 13" tires?

[bdichristina]

Good evening SunLine friends.

We have a 1984 T-1750 travel trailer which came stock with 13" wheels and tires. The previous owner swapped the original wheels and tires with an Aries K car, before sending the car to the junk yard. The wheels fit alright as they are the same bolt pattern, but the tires are passenger car tires. Either they have a bit of dry-rot starting, or the side walls have begun to brake down because they are all cracking on the sides. To boot, three of the four are P165/80R-13; the fourth is a P155/80R13. Needless to say, we are replacing both the wheels and tires before we take this trailer anywhere.

I had shopped and decided on a set of four ST175/80D-13 (load range B - 4 ply, 1100 lb), which I believe is the suitable replacement to the stock B78-13-B tires that equipped all the 1984 travel trailers of less than 24 feet. And these will be pre-mounted on classic, white spoke, wagon wheels.

My question is; can I upgrade the 13" tires to a 14" ST205/80D-14 (load range C - 6 ply, 1760 lb)?

The width and height are well withing my wheel well clearance with plenty of room for spring travel. They will be riding on brand new equalizers, shackles, u-bolts and leaf springs. This will bring the trailer up just over an inch, which will put it just about level with my Grand Cherokee 4x4 tow vehicle.

What got my attention and prompted the question is that the vender has the 14" tire/wheel sets on sale. Not that I'm cheep when it comes to safety; in fact I tend to over spend in that respect. But if I can get the higher rated tires for less than I can get stock, I'm going to consider the upgrade.

So... does anyone see a down side to going with the 14's over the 13's???
_________________
Bob & Kathy
Western New York
1984 Sunline T-1750
2004 Jeep Grand Cherokee Laredo

[bdichristina]

These are the tires on the forest or driver side. The rear tire is the smaller 155:



Below is the camp or passenger side:



This ST175/80D-13 is what I believe to be close to stock:



Specs:
Rim dimensions: 13" diameter x 4-1/2" wide
Bolt pattern: 5 on 4-1/2"
Wheel bolt size: 1/2"-20
Pilot diameter: 3.19"
Tire size: ST175/80D13
Section width: 6.6"
Outer diameter: 24"
Capacity:
Load range: B
Ply rating: 4
Maximum load: 1,100 lbs at 35 psi

This is the ST205/75D14 I want to use:



Load Range: C (6-ply)
Max. Capacity: 1760 lbs. each
Overall Diameter: 26.3"
Maximum PSI: 50 lbs.
Rim Finish: Painted White, Spoke Pattern, 3-1/8" Center Hole
Lug Pattern: 5 Lug on 4.5" Bolt Circle

I have till Monday to decide. If anyone has any reason why I shouldn't upgrade to the 14", please let me know.
_________________
Bob & Kathy
Western New York
1984 Sunline T-1750
2004 Jeep Grand Cherokee Laredo

[Sunline Fan]

I was curious about upgrading from 14" to 15" on a '94 I had. It had the 14" from the factory, but 15" came on the larger trailers (25' and up).

I asked that question to Gary Hertzog, the parts manager at Sunline at the time. He said it should be no problem to do that, because the wheel wells and axle spacing should be the same between the two size trailers. I don't know if this would still be the case for 1984, ten years older than mine. I believe I recall that the longer trailers in 1984 also had 15" tires, and they just used 13" and 15" instead of 14/15.

[quaddriver]

My boat trailer came with 13" load range C tires in 175, and from tire rack I found radials in 185 load range c. the extra 120lbs carrying per tire made me feel a lot better

[Stauggie16]

bdichristina - I am looking to upgrade my wheels and tires on my 1986 Saturn and am curious about what you ended up putting on your TT?

[bdichristina]

Even though the 14" would have fit fine and would have made a beautiful towing trailer even better, I went with the 13" for the following reason.

When we brought her home the day we bought her, she rode "nose-up" to my Jeep Cherokee tow vehicle, which has a straight ball in the hitch. I would have needed a 4" drop hitch to make her ride level.

As I mentioned above, the 14" tire was an inch taller than the 13" tire. The installation of the new equalizers and leaf springs brought her up another 2 inches. My thought was that I would gain 3 inches over all with 14" tires, bringing her to within an inch of my straight hitch height.

What I didn't measure when I first started this thread, was the height of the car tires and rims the trailer came with. These were almost 2 inches shorter than the 13" tires I had shopped. Had I gone with the 14" tire, the trailer would have rode "nose-down" on the hitch.

With the new springs and the new 13" tires and wheels, the Sunline's frame is almost perfectly perpendicular to the road when she is on the Cherokee's hitch. We've put about 300 miles on the new hardware in the last 2 weekends (8/19/11 & 8/26/11), and she tows straight and true. Even with the Jeep's V6, I have to remind myself she's back there.

If we had a variable height hitch, I would have gone with the 14". But I have no complaints with the 13" and the nice level ride they have provided.

***A note on the springs and equalizers - being a 1984, I found the original springs and equalizer had a lot of play to them. After busting more than one knuckle to cut through the old shackle bolts, I found the mounting holes in the equalizers to be oblong instead of round. The bushings in two of the four springs were all but gone and one of the springs had been broken and fell apart in my hands. The cost of the replacement kits, along with new u-bolts and plates for the axles was tiny compared to the safety gained for the family.

I see quite a bit of concern about hubs in those of us rebuilding vintage or aging trailers. I urge you to look six inches farther to the springs, shackles and hangers as well. One lost camper to sloppy suspension is one too many!

_________________
Bob & Kathy
Western New York
1984 Sunline T-1750
2004 Jeep Grand Cherokee Laredo

[Stauggie16]

Thank you so much for all the detail. And especially the advice about the springs and suspension. All good stuff!