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


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 04-20-2016, 04:07 PM   #1
Senior Member
 
Swinepartner's Avatar
 
Join Date: Feb 2014
Location: Zebulon
Posts: 169
18" vs 20"

I am looking to get a new 3/4 ton TV soon. Can someone explain pluses/minuses of these two tire sizes? Vehicle will most likely be a GM product 6.0, maybe the Ram 6.4. I've done a 5 page search on this, but couldn't find anything. Thanks.
__________________
Kevin "Corndog" Cameron
2016 Ram 2500 CTD TRADESMAN
2015 Jayflight 28BHBE
Swinepartner is offline   Reply With Quote
Old 04-20-2016, 04:18 PM   #2
Senior Member
 
Bookemdanno's Avatar
 
Join Date: Jan 2015
Location: DFW
Posts: 3,493
Sorry, I can't really tell you what the difference would be. My 3/4 Ram came with 20" rims with Firestone Transforce AT's. I haven't been real happy with how the Firestone's have been wearing, as I only have just over 10k miles on my truck.
__________________
Dan
'24 GMC 2500 AT4X AEV Edition
Bookemdanno is offline   Reply With Quote
Old 04-20-2016, 04:28 PM   #3
Senior Member
 
Join Date: Jul 2015
Location: Mid-Mi
Posts: 1,492
Kevin,

The biggest difference between the two is the available replacement tire choices. A few more available in the 18" last I have looked. But I am also trying to go with a slightly larger tire than stock which limits choices without any t-bar cranking and or rubbing.

If the new GM trucks with the 20's still have the Goodyear SR-A's as the stock tires, they aren't the best. They didn't seem to bad the first 20k miles or so, but this last winter they seemed like they turned to junk as far as traction. I am only trying to get through this summer before replacing them.

Will you be buying off the lot, or ordering? Don't rule out a 3500 SRW regardless is ordering or off the lot. Price is usually about the same, and you will gain a fair amount more available payload.

Good luck!!!
__________________
Bubba J- '13 Chevy Silverado 2500HD LT CCSB 4x4 6.0

'16 Jay Flight 32 BHDS ELITE 32 BHDS MODS Reese DC HP

WDH SET UP. HOW A WDH WORKS. CAT SCALE HOW TO.
need-a-vacation is offline   Reply With Quote
Old 04-20-2016, 04:35 PM   #4
Senior Member
 
SmokerBill's Avatar
 
Join Date: Sep 2010
Location: PNW
Posts: 5,195
From what I've seen, smaller rim sizes on trucks (RAMs, at least) give the truck more tow (or payload) capacity. At least that was the case when I was doing comparisons when shopping for my truck.
__________________
Bill
2011 Dodge Ram 1500 HEMI Quad Cab
2011 Jay Flight 26BH
SmokerBill is offline   Reply With Quote
Old 04-20-2016, 06:02 PM   #5
Member
 
Join Date: Mar 2016
Location: Grand Bend
Posts: 48
If the overall diameter is the same which I suspect it will be, with this 20 inch tire you will have a lower profile (less rubber between the rim and the road). The 18s will give you more capacity, better ride, and less expensive tires, they just won't look as cool! To help you make up your mind price out replacement tires in both sizes.
hoss10 is offline   Reply With Quote
Old 04-20-2016, 06:07 PM   #6
Senior Member
 
Join Date: May 2013
Posts: 1,588
If you're rocking a crew cab with a 6 or 8 foot bed then 20's will look more proportioned to that size of truck. Outside diameter and total wheel weight are two contributing factors to towing performance but with today's engines and transmissions the effect will be minimal. Having more rim and less rubber sidewall (as with a 20in) will provide a stiffer ride and more stable towing than an 18 with more rubber side wall to flex. I love my 20's wrapped in 33.5in mudders!
__________________
2013 F-150 EcoBoost MaxTow, Roush tuned (415hp 506tq), lifted on 33s, R.A.S.
2013 Jay Flight 28BHS Elite (Equalizer 10K hitch)
SkyBound is offline   Reply With Quote
Old 04-20-2016, 06:12 PM   #7
Moderator Emeritus
 
Rustic Eagle's Avatar
 
Join Date: Apr 2011
Location: Michigan
Posts: 9,424
I have new GM 2500HD on order and I went with the 18" rim/tire option in lieu of the OEM standard 17". I didn't put any do-diligence into considering the 20" rim/tire because I would be closing in on my garage door clearance height.

I'm somewhat old school in thinking, but I would think that GM has the 2500HD drivetrain (engine/transmission/axle ratio, etc.) optimized based on the "standard" components offered, i.e.; 17" rim/tires.

I remember back a few years Ford's publications stated that going from a 17" rim to a 20" rim reduced payload capacity by 500lbs....., I believe it was even reflected in their "build your own" tool. But since the start of the recent Big Three towing wars, I haven't run across this reduction statement.

I would assume that a 20" rim with a "larger tire diameter" (taller tire) then the OEM standard 17" tire diameter, the effective gear ratio would be reduced (IMO very little). I don't know the GM OEM 17" and OEM 20" tire diameter differences (if any).

Bob
__________________

2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)
Rustic Eagle is offline   Reply With Quote
Old 04-20-2016, 06:25 PM   #8
Senior Member
 
Join Date: Dec 2015
Location: Houston
Posts: 781
I agree with some of the others. I have the 19.5 inch wheels and the larger tires are VERY expensive. But, I have to disagree with load capacity comments.
__________________
2016 Jayco Eagle 330RSTS = "Madame Maxime"
Maxxis M8008 E rated Tires and 16" Wheel Upgrade
Dual A/C 15K BTU, 14K Equalizer WD hitch with SC
King Bed with Java Interior, (2X) Yamaha EF2000isV2
2012 Ram 4500, 6.7L Cummins Turbo Diesel, MegaCab = "Hagrid"
8'x12' BMCM Stake Bed, Cabin Chassis, 2WD
360 degree Virtual Tour
Fairenatic is offline   Reply With Quote
Old 04-20-2016, 06:29 PM   #9
Senior Member
 
Join Date: Apr 2015
Location: winnipeg
Posts: 257
Quote:
Originally Posted by hoss10 View Post
If the overall diameter is the same which I suspect it will be, with this 20 inch tire you will have a lower profile (less rubber between the rim and the road). The 18s will give you more capacity, better ride, and less expensive tires, they just won't look as cool! To help you make up your mind price out replacement tires in both sizes.
I think we need to add this to the controversial posts list because looking "cooler" is definitely a personal preference. I've always thought low profile tires with big rims can look great on a sports car but I like rubber on my trucks. Still think it looks good, don't get me wrong but it falls into the category of low rider trucks. Not for me.
__________________
2015 29QBS
2015 Sierra 2500 6.0l
2009 Silverado (gone and missed!)
canadiankid is offline   Reply With Quote
Old 04-20-2016, 07:15 PM   #10
Senior Member
 
Paintinfool3's Avatar
 
Join Date: Apr 2014
Location: Fort Wayne
Posts: 1,271
I have 20 inch rims on my newer F250 and although the tires were more expensive and they are taller I don't believe they are much lower profile tires
__________________
2011 F250 King Ranch Crew Cab Diesel , 2015 Jayco Eagle 338 rets
Paintinfool3 is offline   Reply With Quote
Old 04-20-2016, 07:24 PM   #11
Senior Member
 
Join Date: Apr 2015
Location: winnipeg
Posts: 257
Quote:
Originally Posted by Paintinfool3 View Post
I have 20 inch rims on my newer F250 and although the tires were more expensive and they are taller I don't believe they are much lower profile tires
It all really depends, it doesn't have to be lower profile but depending on tire clearance (not to rub mud flaps) the outside diameter can only be so big. Add a lift=make more room. On my GM I'm pretty much maxed out for tire size at the 275 70 18 so if you went to 20's you would need less rubber to fit without rubbing.
__________________
2015 29QBS
2015 Sierra 2500 6.0l
2009 Silverado (gone and missed!)
canadiankid is offline   Reply With Quote
Old 04-20-2016, 07:33 PM   #12
Senior Member
 
Paintinfool3's Avatar
 
Join Date: Apr 2014
Location: Fort Wayne
Posts: 1,271
here's the 20 inch tires on mine
Attached Thumbnails
20151231_140617_resized.jpg   20151231_140626_resized.jpg  
__________________
2011 F250 King Ranch Crew Cab Diesel , 2015 Jayco Eagle 338 rets
Paintinfool3 is offline   Reply With Quote
Old 04-20-2016, 08:30 PM   #13
Senior Member
 
Join Date: Jul 2015
Location: Mid-Mi
Posts: 1,492
Kevin,

The overall diameter, regardless of the rim size, will be very close to each other. The difference is very small, similar to the differences in size between two manufactures tires of the same size.

The following specs are from a generic tire size comparator.

265/70/18 specs are: 32.6" diameter, 10.43" wide, 7.3" sidewall, and 102.4" circumference.
265/60/20 specs are: 32.5" diameter, 10.43" wide, 6.26" sidewall, and 102.1" circumference.

As you can see, the differences are small.

Concerning the weight capacity of the tire, yes, there are differences, which could affect the payload of the truck. It depends on the actual tire and size. A 265/70/18 has a weight capacity of ~3500lbs, while a 265/60/20 has a capacity of ~3200lbs. I haven't shopped the new '15 or '16 Gm Twins, for the '13 and '14 GM Twins, the 20" rims were not available from the factory on the 3500HD's, only the 2500HD's due to the weight capacity of the stock tire. But there are other 20" tires that have a higher weight capacity.

Had we ordered our truck, I probably would not have opted for the 20's, but buying off the lot limits some choices. Even more so when buying at the end of a model year. Reason being is the available replacement tire choices for the 20's. The selection is getting better though!
__________________
Bubba J- '13 Chevy Silverado 2500HD LT CCSB 4x4 6.0

'16 Jay Flight 32 BHDS ELITE 32 BHDS MODS Reese DC HP

WDH SET UP. HOW A WDH WORKS. CAT SCALE HOW TO.
need-a-vacation is offline   Reply With Quote
Old 04-20-2016, 09:56 PM   #14
Senior Member
 
Join Date: Feb 2014
Location: MD
Posts: 3,856
18" vs 20"

Quote:
Originally Posted by Rustic Eagle View Post

I would assume that a 20" rim with a "larger tire diameter" (taller tire) then the OEM standard 17" tire diameter, the effective gear ratio would be reduced (IMO very little). I don't know the GM OEM 17" and OEM 20" tire diameter differences (if any).

Bob

The rim size doesn't dictate the overall diameter on oem equipped vehicles. A GM 17" wheel package and a GM 20" wheel package offered on the same truck will have the same overall diameter. The 17" package will have more tire sidewall and the 20" will have less tire sidewall so both will be about the same overall diameter. Ever notice the spare tire rim size doesn't necessarily match but the spare tire's overall diameter does?
__________________
2017 JayFlight 28BHBE
2014 JayFlight Swift 264BH (Sold)
2007 GMC 2500 Sierra Classic Crew Cab LBZ Duramax / 6spd Allison
SouthCo is offline   Reply With Quote
Old 04-21-2016, 06:27 AM   #15
Member
 
Join Date: Mar 2016
Location: Grand Bend
Posts: 48
Quote:
Originally Posted by Paintinfool3 View Post
I have 20 inch rims on my newer F250 and although the tires were more expensive and they are taller I don't believe they are much lower profile tires
Pretty easy to check if they are 50, 55, or 60 tires as opposed to 70 or75 ( the last number on the sizing), then they would be considered low profile tires.
We live on a farm and never run low profile tires, The gravel roads and potholes are very hard on the rims.
hoss10 is offline   Reply With Quote
Old 04-21-2016, 06:36 AM   #16
Moderator Emeritus
 
Rustic Eagle's Avatar
 
Join Date: Apr 2011
Location: Michigan
Posts: 9,424
SouthCo,

Quote:
Originally Posted by SouthCo View Post
snip...... A GM 17" wheel package and a GM 20" wheel package offered on the same truck will have the same overall diameter.....snip
I would tend to agree with the logic behind GM having the same overall diameter...., but, when I ordered my 2016 2500HD the GM 17" wheel package came with a 245/75R-17E tire and the GM 20" wheel package with a 265/60R-20E tire....., these two tire sizes reflect little over a 1" overall diameter difference.

Bob
__________________

2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)
Rustic Eagle is offline   Reply With Quote
Old 04-21-2016, 06:43 AM   #17
Senior Member
 
Paintinfool3's Avatar
 
Join Date: Apr 2014
Location: Fort Wayne
Posts: 1,271
Its amazing to me all the wheel diameters and styles they offer on the new gm trucks. I work at the Fort wayne assy plant a few days a week and see all kinds and sizes of tire wheel combos go down the line. Today with the computers on trucks and cars I am sure they can set the speedometer to read correctly through the programming done towards the end of the line based on wheel diameter
__________________
2011 F250 King Ranch Crew Cab Diesel , 2015 Jayco Eagle 338 rets
Paintinfool3 is offline   Reply With Quote
Old 04-21-2016, 07:05 AM   #18
Senior Member
 
Join Date: May 2013
Posts: 1,588
There are many different rim and tire size combinations offered by manufacturers on the same truck. These combinations will yield slight differences in overall diameter; maybe an inch or two. A small change in diameter will affect torque output, but only marginally since today's towing engines are powerful and transmissions have 6+ gears.

On my Ford, the dealership can only recalibrate the speedometer if the new wheel diameter is equal to one of the stock options available on the truck from the manufacturer. If it's an aftermarket size, the only way to truly recalibrate the speedo is with an aftermarket tuner or programmer.
__________________
2013 F-150 EcoBoost MaxTow, Roush tuned (415hp 506tq), lifted on 33s, R.A.S.
2013 Jay Flight 28BHS Elite (Equalizer 10K hitch)
SkyBound is offline   Reply With Quote
Old 04-21-2016, 07:38 AM   #19
Senior Member
 
Join Date: Jun 2015
Location: Orem
Posts: 113
Larger Rim Equals Smaller Suspension

If the rims are larger and the overall circumference is the same, then the sidewall is smaller. If the sidewall is smaller, there is a smaller volume of air in the tire. The larger volume of air in the tire provides a better suspension.

The 20" tires do not provide as much suspension. The ride will be stiffer and there will not be as much give when the tires hit bumps or traveling on dirt roads.

The 20" tires are for looks and would not be found on a rig that was meant for work. Like pulling a heavy trailer.
__________________
2008 Jayco 24 RKS
2012 Suburban
marbles is offline   Reply With Quote
Old 04-21-2016, 08:08 AM   #20
Senior Member
 
Join Date: Jan 2016
Location: Howard city, MI
Posts: 101
I would have to agree that more of a sidewall on the tire will give you a higher load capacity. For instance I have 20 inch tires on my truck and they are load range E with a load capacity of 2833lbs per tire at 80 psi max. If you were to have the same tire in an 18 inch wheel the load capacity is 3640lbs per tire at 80 psi. With that being said I pull our 5th wheel with no issues with 20inch tires.
Attached Thumbnails
2016-04-17 10.54.32.jpg  
__________________
Jason
------------
2016 Eagle HT 29.5bhds
2015 F250 Lariat 6.7 diesel
Camping_J is offline   Reply With Quote
Reply

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


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Jayco, Inc. or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 05:23 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright 2002-2016 Social Knowledge, LLC All Rights Reserved.