Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > iRV2.com COMMUNITY FORUMS > iRV2.com General Discussion
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 01-12-2019, 08:29 PM   #15
"Formerly Diplomat Don"
 
Dutch Star Don's Avatar
 
Newmar Owners Club
Join Date: Apr 2005
Location: Moorpark, Ca.
Posts: 20,643
Quote:
Originally Posted by Calbar View Post
235 is the tread width in mm not the height. The 80 or 85 number is the height percentage so tire width will be identical just a bit taller.

245 would be a wider tire than the 235 by 10 mm.

Rob
You might want to check your what you wrote. Please show me a 235/85 x 15 that is the same width as a 235/50 x 15. As one size gets wider the other gets shorter. One is a ratio of the other.
__________________
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor
Dutch Star Don is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 01-12-2019, 08:47 PM   #16
Registered User
 
Join Date: Mar 2015
Location: LA, Lower Alabama
Posts: 2,430
Quote:
Originally Posted by Dutch Star Don View Post
You might want to check your what you wrote. Please show me a 235/85 x 15 that is the same width as a 235/50 x 15. As one size gets wider the other gets shorter. One is a ratio of the other.
How's this

Image result for tire size explainwww.lesschwab.com
The first three-digit number in the tire size refers to the tire width. For instance, in a size P215/65 R15 tire, the width is 215 millimeters. ... For example, in a size P215/65 R15 tire, the 65 means that the height is equal to 65% of the tire's width. The bigger the aspect ratio, the bigger the tire's sidewall will be.
Understanding Tire Sizes | Just Tires
http://www.justtires.com/content/con...eName=TireSize
chunker is offline   Reply With Quote
Old 01-13-2019, 05:32 AM   #17
IC2
Senior Member
 
IC2's Avatar


 
Join Date: Jun 2010
Location: Upstate New York
Posts: 3,690
Quote:
Originally Posted by Theunz View Post
I, along with many on the Montana Owners forum have gone to the Sailuns which come in both 80 and 85 series. I went with the 85s with no problems. Research the Sailun tires, as they have a stellar reputation and cost significantly less than the Goodyear G rated tire. The difference in weight between the Sailuns and the OEM tires was noticeable.
The only downfall of this very fine tire is that unless a towable has 110psig rated wheels, you can't get all of the benefits, Many 5ers like mine have 94 psig Sendel or similar wheels used for 80 psig tires - and why our 5er has SOB (NOT Tow Max China Bombs). There is a Sailun S637 inflation chart somewhere but I couldn't find it this morning
__________________
Dave W
2011 Ford F250 6.7 Lariat CCLB, 5er Hitch Option w/ Rite air bags,

2014 Montana High Country 343RL (sold it!)
IC2 is offline   Reply With Quote
Old 01-13-2019, 06:13 AM   #18
Member
 
Calbar's Avatar
 
Join Date: Dec 2018
Posts: 40
Quote:
Originally Posted by drwwicks View Post
How's this

Image result for tire size explainwww.lesschwab.com
The first three-digit number in the tire size refers to the tire width. For instance, in a size P215/65 R15 tire, the width is 215 millimeters. ... For example, in a size P215/65 R15 tire, the 65 means that the height is equal to 65% of the tire's width. The bigger the aspect ratio, the bigger the tire's sidewall will be.
Understanding Tire Sizes | Just Tires
http://www.justtires.com/content/con...eName=TireSize
Thanks drwwicks.

Rob
Calbar is offline   Reply With Quote
Old 01-13-2019, 09:59 AM   #19
Senior Member
 
FastEagle's Avatar
 
Join Date: Sep 2009
Posts: 1,523
Quote:
Originally Posted by IC2 View Post
The only downfall of this very fine tire is that unless a towable has 110psig rated wheels, you can't get all of the benefits, Many 5ers like mine have 94 psig Sendel or similar wheels used for 80 psig tires - and why our 5er has SOB (NOT Tow Max China Bombs). There is a Sailun S637 inflation chart somewhere but I couldn't find it this morning
http://fifthwheelst.com/documents/Co...T-Modified.pdf
FastEagle is offline   Reply With Quote
Old 01-13-2019, 04:31 PM   #20
PKI
Senior Member
 
PKI's Avatar
 
Join Date: Oct 2018
Posts: 878
A 1/2" increase in tire height places all of the coach and it's contents higher from the road surface, which is less stable and only helpful if ground clearance is required by your travel (off road, ruts, chuck holes, approach angle).

Another issue with increasing the tire size is that brake power decreases. The lever arm is more, so the coach takes more force from the brakes to decrease speed.

The change in aspect ratio reduces the sidewall stiffness. Some tires are designed with additional strength in the sidewall as is the case with truck tires vs passenger car tires. That might be a consideration to talk over with a tire expert.

The value of a bigger tire is the weight capacity increase, that you have identified. That should improve reliability as well. My preferance would be wider and lower aspect, but there are often very few options.

Weight verification is not difficult on an axle to axle basis. A standard CAT scale has three pads, spaced to weigh the steer axle, drive axle and the trailer. Takes multiple passes to get weights on all RV axles. Getting left and right weights is more difficult. The standard CAT scale is usually gated to not allow an offset pass for one side weights. There are supposed to be services that have individual scales to weigh all wheel positions. Maybe someone has a contact they would share.

Research this question with the tire guys for better information, as I used to think wider tires gave you better traction on ice.
__________________
Travel Safe and with a Smile! Pat
2020 Tiffin Breeze 33BR
2022 Cherokee Trailhawk toad
PKI is offline   Reply With Quote
Old 01-13-2019, 05:50 PM   #21
Moderator Emeritus
 
Gary RVRoamer's Avatar


 
Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 25,066
As long as you have enough room under the fenders and between the two axles (so the tires don't rub each other), I don't think the extra 0.9" in diameter will make any material difference. The slight gain in load capacity is also insignificant, though more capacity is always better. The taller tire will run a few less revolutions per mile (19, says the size calculator) so maybe runs a tiny bit cooler, but again insignificant in the big picture.
__________________
Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL
Gary RVRoamer is offline   Reply With Quote
Old 01-15-2019, 11:48 AM   #22
Senior Member
 
FastEagle's Avatar
 
Join Date: Sep 2009
Posts: 1,523
Quote:
Originally Posted by wingnut60 View Post
Most just put on cheapest tires that can carry the rated weight on the axles.

Not any more. That is, if they want to keep their membership status in RVIA.


Starting right at the end of model year 2017. All RV trailer manufacturers that are members of RVIA (98%) were required to provide original equipment tires - via inflation - with load capacities 10% above the trailer's vehicle certified GAWR (s). What that would boil down to; is a 5200# axle would be fitted with two tires that provide more than 2860# each for that axle fitment.


Brands are only a marketing tool of the industry. In the regulations world an equally designed, designated size, such as ST225/75R15 LRD is equal in load capacity to all others of the same size and design.
FastEagle is offline   Reply With Quote
Reply

Tags
switch, trailer



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
2008 Winnebago Destination Series M-37G-W or 2006 Allegro Bay Series M-37DB Workhorse jrt13 iRV2.com General Discussion 4 11-05-2016 06:40 PM
Series/Parallel or Parallel/Series rpasetto Monaco Owner's Forum 45 09-28-2011 12:52 AM
Series/Series Parallel CARVAL Motorsports MH-General Discussions & Problems 7 01-28-2009 12:02 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 10:22 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.