T-2753 Tire Size

[Sunny Side Up]

Hello Everyone,
We're planning on buying new tires for our 2005 T-2753 this spring and I have a few questions about tire size. The original tires on our trailer are size ST 205/75 R 15 load range C. Is it possible to fit size 235/75 R 15 on the stock rims, and is there enough room between the axles and wheel wells?

Also, how does everyone feel about substituting LT (light truck) tires for use on travel trailers.

Thanks in advance! and happy camping
BLT

[henryj]

Generally speaking tires perform well when the tread width is the same as the wheel width. Given that our 15X5 wheels are already on the narrow side for a 205 tire, I'd stay away from 235. A narrow wheel/wide tire combo makes for a very flexible sidewall regardless of tire pressure. On a trailer this combo would allow your trailer to squirm side to side which is the precursor of sway. The wheelwell clearance may not be enough for a wider tire either.

Check our recent discussion on http://www.sunlineclub.com/forums/f7...html#post92227 to look at other possibilities.

Henry

[JohnB]

Hi Bart

I believe your stock tires Sunline put on are rated at 1,829# at 50psi. And that lines up with the way Sunline installed running gear and tires. The tires, axles and suspension can handle the entire GVWR of the camper. In your case 7,000# GVWR. Since the truck holds the tongue weight and if you keep your TT at or under the fully loaded GVWR of 7,000# your axle will never see 7,000# but pending loading 1 side may have issues if unevenly loaded. Not all TT brands ahere to that way of saftey ratings and I'm glad Sunline did as it gies us some extra saftey factor and freedom to load the camper the way the space allows us to left to right but yet not get to far out of uneven.

See here for what was on my 2004 T2499. The same ST205/75R15’s which are 27.1” OD. http://www.maxxis.com/Industrial/Trailer/M8008-ST-Radial.aspx Look under the spec tab

My T310SR came with ST225/75R15’s rated at 2,540# at 65 psi and they line up with my 10,000# GVWR.

In your case I see 2 issues up’ing the tires size.

Pressure. I do not know which tire your are looking at but those ST 235/75R15’s from who’s ever brand may be 65 psi rated. I know the rims on my T2499 where only 50 psi rims and they are 5 lug nut rims which I am fairly sure yours are too. My ST225/75R15’s are 65 psi rims and 6 lug nut rims. The heavier rated tire carries higher pressure, higher rated rims and needs a larger axle to go with it creating the need for a 6 lug. So it may force you to a 65 psi rim and I do not know if they come in 5 lug.

Diameter. My prior T2499 had the ST205/75R15’s which are 27.1” OD. My ST225/75R15’s are 28.3”. Sunline used different then industry standard axle centers. Meaning the distance from front to rear axle. Right now on your ST205/75R15 you have a gap between the tires that will decrease at least 1.2” less if you changed to at least the Maxxis ST225/75R15. Do not know the OD of the ST235/75R15’s your looking at. My concern is since you have 3,600# springs even if the heavier rated tire the springs still flex like 3,600# springs. The bump clearance when the springs flatten some my be cutting it close if the 2 tires are a lot closer together. And then there is the fender height/wheel well issue. Sunline built low rider campers so they have less wind drag. If you eat up over an inch in fender clearance that “might” be a problem. I know Dexter recommends that a minimum of 3” be used for wheel well clearance. I cannot remember the T2499 but I do know my T310SR does not even have 3”, more like 2 1/2" and I would not want to go any less then that as you can bottom out under the right conditions going up and over a bump/pot hole at much less then 2 to 2 1/4" . You could measure the wheel well clearance you have now and see what the OD will reduce it by. Again I would not recommend anything less what I have, the 2 1/2”

Now as you can see by the link Henry pointed you too, TT’s manufactures are now installing LT tires as stock tires. And on that link they had 50 psi rated LT235/75R15’s D rated. Do not know the OD but they are on 6 lug rims as I count the lug nuts in the pics. They may have 50psi tires on 65 psi rims??? Which is OK to do.

If you can find an LT tire that has the 50 psi pressure at max cold pressure and same OD as what you have now, then that would not be a problem from what I have found so far on LT tires. Finding a tire like that may be the problem. I’m in the same boat now myself if I ever what to switch to LT’s, even if I have 65psi rims. I have not been able to “yet” find a tire in my same size to make the switch. And going to 16” tires which has many LT options I cannot deal with the tire to tire clearance or the fender height clearance. I hope to sort this out in about 3 years when I need new tires....

Good luck and hope this helps. If you find something let us know.

John

[JohnB]

Bart

I have a "foggy" memory that EMAN here on SOC may have converted to LT tires on his T2499. But he also had a specail axle ride height change from Sunline. He had I think a higher starting angle on his rubber torsion axles. I'm assuming you are on leaf springs. Which if so, an axle flip kit can gain you about 4" more fender clearance. Still have to verfiy if the tire to tire distance between the axles is OK.

I'll see if I can find EMANS post on the LT switch or he was thinking about it and never did it.

[JohnB]

Bart

I got lucky and found one of EMAN's posts. Well at least in this post he did not yet go LT. See post 17 with his reply

http://www.sunlineclub.com/forums/f7...html#post81532

He is still in the C range, still 50psi but the ST225/75R15. Not as wide as the 235's but they are 28.3" OD and on his lifted trailer and torsion axles it seems to work.

On The Wings of Goodyear | RV Tires - Tire Selection - Marathon®

John