Upgrading to 17.5 Inch Tires/Wheels

[Bigsky3625RE]

Greetings. Been doing some research on what it takes to upgrade for a larger safety margin.

Currently have a 3625RE with the Big Sky package. So the tires and rims are upgraded to the GY G614.

How do I find out the axle ratings and lug size? A lot of threads talk about using trailertiresandwheels.com, but to order I need to my lugs size and hub diameter which I have no clue where to find.

Any help would be greatly appreciated!!

[DQDick]

Try calling Tredit Tire. They sold Keystone the ones you currently have on.

[Exnavydiver]

I already did the research for our Big Sky, the rims for the 17.5s require 9/16 inch lugs, you currently have 1/2 inch. The 17.5 Goodyear would be the G-114 will give you 4705 lbs per tire which is a great safety margin. I just didnt have the bucks to go that route so I am using the 614s at the moment. If we get the IS system then we will go the 17.5 route then..

[7.3Ford]

You might want to check out Greg's post. He did go to IS at the same time.

http://www.montanaowners.com/forums/...ad.php?t=52072

[Bigsky3625RE]

quote:Originally posted by Exnavydiver

I already did the research for our Big Sky, the rims for the 17.5s require 9/16 inch lugs, you currently have 1/2 inch. The 17.5 Goodyear would be the G-114 will give you 4705 lbs per tire which is a great safety margin. I just didnt have the bucks to go that route so I am using the 614s at the moment. If we get the IS system then we will go the 17.5 route then..

Thanks for the info on the lug size. I know if i go the Alcoa route the lugs would need to be upgraded as well.

Here is a link for a17.5 Hi-Spec rim that you can get with 1/2 lugs. This would work if the hub is 4.9.....correct?

http://www.trailertiresandwheels.com...-trailer-wheel

[Gkerlin]

you can get either wheel with 1/2" or 9/16" studs. You just need to specify what stud you have.

I put Alcoa 17.5's on my trailer a few months ago.

[mhs4771]

If you look at the side of the lug nuts they may be marked. Most likely 1/2 inch for standard drum brakes and 9/16 for disc brakes. Just went thru that upgrade on our SOB last month. Ordered 5 tires and wheels from Trailer Tire and Wheels. Very easy to work with.

[Bigsky3625RE]

Thanks for everyone's input and I confirmed the lug size.

I called Keystone and within 5 minutes had the lug size (1/2-20) and axle size (7K).

So next step will be placing my order for the new wheels and tires.

[Exnavydiver]

When I did my research I referenced Trailer Tire and Wheel as my main source of information. At the time I was told that they were coming our with the 1/2x 20 but did not have them at the time. Now I am disappointed that I didn't wait. LOL, well live and learn..

[8e3k0]

Nice to go the 17.5 route and get 4705 lbs per tire or total tire capacity of 9410 lbs per axle; but your axles are rated for 7000 lbs so your only gaining load capacity at the wheel and not at the axle. Many horror stories with bent axles with overloading, impact loading etc. When I looked into the 17.5s, I would of jumped to 8000 lb axles with hydraulic brakes all inclusive. That's when it gets really expensive!!! In conclusion and as an alternative, I installed, wet bolts, grade 8 u-bolts and nuts, added another leaf to each leaf pack, shocks, plus the x-factor cross members front center and rear. Axles and Monty trail well with little to no wear on LT tires that have about 25,000 miles on them now.

[Bigsky3625RE]

quote:Originally posted by 8e3k0

Nice to go the 17.5 route and get 4705 lbs per tire or total tire capacity of 9410 lbs per axle; but your axles are rated for 7000 lbs so your only gaining load capacity at the wheel and not at the axle. Many horror stories with bent axles with overloading, impact loading etc. When I looked into the 17.5s, I would of jumped to 8000 lb axles with hydraulic brakes all inclusive. That's when it gets really expensive!!! In conclusion and as an alternative, I installed, wet bolts, grade 8 u-bolts and nuts, added another leaf to each leaf pack, shocks, plus the x-factor cross members front center and rear. Axles and Monty trail well with little to no wear on LT tires that have about 25,000 miles on them now.

True statement....not looking to increase axle load. That would require an axle with a larger load rating. No need to go that route.

Have the wet bolt installed with the MorRyde suspension. Part of the Montana / Big Sky upgrade.

We travel pretty light and use a TST TPMS monitor.

So just looking to get some better rated tires and wheels under our Big Sky as we start to put some miles behind us!!!

[Exnavydiver]

I had no intention of increasing axle load, I wanted the largest safety buffer on the tires I could get and the 17.5s supplied that. The G614s are good, but the 17.5 G114s make a huge difference in margin.

[Gkerlin]

For every post about an axle problem there are probably 50 about a tire blowing out.

[dmacy]

Here is what I went with. http://www.southwestwheel.com/store/...er-wheels.aspx. Added Goodyear 614 215/75r/17.5 tires and hub piloted 12 inch drums for the 7,000 lbs axle with 9/16 inch studs. GREAT UPGRADE! but expensive. The only way to go. don't forget about spare. The only down side is keeping the Alcoas clean and waxed. I would recommend this upgrade to any one

[dmacy]

The posted link doesn't work. Try this one. http://www.southwestwheel.com/store/...b-piloted.aspx

[Art-n-Marge]

Assuming one gets large wheels and tires on the 6,000 or 7,000 lb axles, does one have to be concerned how much weight increase is now at the end of the axles if the new wheels & tires weigh more than the smaller size?

I would imagine that if the axle is rated to carry the weight and one stays under that, the weight is carried at the springs where the axles connect to the rig. But what about if there's more weight at the ends of the axles where the heavier tires are now positioned. How does this small difference affect the endpoints of the axle, or does it?

I realize that adding an IS system is a whole new ball game and it is so strong I have never heard of an "axle" problem with that thing. But axles (and their spindles) have been bent out of shape because of a problem or too much weight contributing to it.

Just curious.

[dmacy]

Wheels and tires are "unsprung weight" and not "sprung weight". Sprung weight is of concern because it has effect on an axle an springs. Unsprung weight has no effect except for stopping. The marginal gain it weight is more than made up for by the increased safety.

[Bigsky3625RE]

Wheels and tires get delivered tomorrow!!! Can't wait.

Thanks for all the posts to help make my decision.

[Bigsky3625RE]

Tires came!! Install tomorrow.

[Bigsky3625RE]

Install went well. It just poured on me the whole time!!

I really like the look. Will see how they pull in a week as we leave for the ocean for a week.





Thanks for everyone's help!!