Hi Guy's,I have one more question before I pull the trigger on my New Truck Factory build THIS WEEK!!.. Yes I need to order it this week on my F350 SRW Powerstroke 6 3/4' bed big cab :-)We're planning a trip to the New England Area from San Diego during the kids summer holidays! :-)The question is regards to the Wheel size and tires..Before we begin, My wife and I REALLY like the look of the 20" Wheels.I looked on the Michelin Website and it looks like here's the two options:- LT 275/70R x 18E Max load 3640Ib @ 80- LT 275/65R x 20E Max load 3750Ib @ 80On paper it says that the 20" can handle more load.From what I understand is that the 70R and the 65R refers to the ratio of the wheel size vs the height of the tire wall with all other things being equal. Therefore with the 20" wheel being 2" bigger then you would expect the ratio to be smaller IF the wall remains the same height.So it looks like these are NOT low profile tires..But what I want to confirm is that the wall is the same height between 18" and 20". Basically I have the same amount of air between the pot hole that I hit and the rim of the wheel.Any other comments on this are very welcome!.. you guys are always so knowledgable! Seriously a part of all of you is going into this truck! LOL :-).. I'll post a photo when it arrived!Thanks!Steve

The 20s are more pricey to replace too. That's why I went with the 18s on my RAM.Up to you though.As an Example:BFG All terrain 275/70/18s 3640# max load - $208 each on tirerack.comBFG All terrain 275/65/20s 3750# max load - $298 each on tirerack.comThat's almost $400 more for a set of 4.The 65 and 70 refer to the ratio of the sidewall height to tread width.The tread width is 275mm for both, so the 20" tires have a sidewall 65% as high as the tread is wide, so 275 x 0.65 = 178.75mm tall = 7.03 inches.275 x 0.7 = 192.5mm tall = 7.57 inches.Overall tire diameter/height:275/70/18 = 33.2"275/65/20 = 34.1"

ib516 wrote:The 20s are more pricey to replace too. That's why I went with the 18s on my RAM.Up to you though.As an Example:BFG All terrain 275/70/18s 3640# max load - $208 each on tirerack.comBFG All terrain 275/65/20s 3750# max load - $298 each on tirerack.comThat's almost $400 more for a set of 4.The 65 and 70 refer to the ratio of the sidewall height to tread width.The tread width is 275mm for both, so the 20" tires have a sidewall 65% as high as the tread is wide, so 275 x 0.65 = 178.75mm tall = 7.03 inches.275 x 0.7 = 192.5mm tall = 7.57 inches.Overall tire diameter/height:275/70/18 = 33.2"275/65/20 = 34.1"THANKS!!! Just after I posted this then found that I had the ratio wrong and came up with the same numbers!! :)So I may now change the question and ask what is the impact on having tired with a 1/2" narrower sidewall?Thanks!

Larger wheel generally will give you a rougher ride. See if the dealer has couple trucks (2500 or 3500srw-any motor) with one of each wheel size. Take them for a drive to compare down the same roads, stay in the same lane, etc.Personally, I would probably go with the 18's. Better tire selection, little better ride, etc. Our truck came w' 20's (bought off lot), and there are a few more tires recently available that will fit our truck (GM's don't like larger tires (much taller) without rubbing). I have been back and forth to switch to 18's for the little better ride and better tire selection. Stock we have 32.5" tall tires, can fit 33" tires, but 34" will rub as I understand.BUT.... If the Ford allows you to mount a taller tire without any issues then go with the rim you like the best. If thats something you would consider.

Need-A-Vacation wrote:Larger wheel generally will give you a rougher ride. See if the dealer has couple trucks (2500 or 3500srw-any motor) with one of each wheel size. Take them for a drive to compare down the same roads, stay in the same lane, etc.Personally, I would probably go with the 18's. Better tire selection, little better ride, etc. Our truck came w' 20's (bought off lot), and there are a few more tires recently available that will fit our truck (GM's don't like larger tires (much taller) without rubbing). I have been back and forth to switch to 18's for the little better ride and better tire selection. Stock we have 32.5" tall tires, can fit 33" tires, but 34" will rub as I understand.BUT.... If the Ford allows you to mount a taller tire without any issues then go with the rim you like the best. If thats something you would consider.Good feedback Thanks!.. this seems to concur with what others are saying..although the 20" look 'cool' the ride is a lot rougher on the 20"My wife has low profile tires on her little Mazda that she runs around in. We both said 'Never Again'.. :-) It sounds like although the 20" are not Low Pro that they will still have some of the same issues.. rougher ride and easier rim damage and even alignment getting knocked out of waco easier by a pot hole!

So far it seems to me that the only argument FOR 20" wheels is 'Looks' and it is undeniable that the 20" 'look cool' However there is a lot more parts to the evasion than looks especially if you use the truck for towing and rough roads. It looks like the sensible thing to do is go with the 18's Anyone going to scream NO!! ? :-)

Wheel Size | Good Sam Community

15 Replies

smcrea
Explorer II
Feb 02, 2015
stsmark wrote:
Having 56000 miles of experience with a CCSB F350 on 20's, a shock upgrade will contribute to the ride more than tire sidewall between the 2 choices when I went to Bilsteins was a noticeable difference. It's an 8000 lb. truck there's only so much to expect in ride quality. I came out of a 2001 SD so it's been like 60's Caddy to me.

I'm on the original set of Michelins btw, going to LTX MS2 in the future as they now make it in a 20. If you're near Sonoma County you can grab mine and tow or try it out all you want.

Enjoy Mark

Thanks Mark! :-)

I'm certainly leaning towards the 20" now!

Show time.. I need to order the truck before Wednesday! :-).. I want it to arrive before the May holiday and take advantage of some more discounts! :-)

Steve
stsmark
Explorer
Feb 02, 2015
Having 56000 miles of experience with a CCSB F350 on 20's, a shock upgrade will contribute to the ride more than tire sidewall between the 2 choices when I went to Bilsteins was a noticeable difference. It's an 8000 lb. truck there's only so much to expect in ride quality. I came out of a 2001 SD so it's been like 60's Caddy to me.

I'm on the original set of Michelins btw, going to LTX MS2 in the future as they now make it in a 20. If you're near Sonoma County you can grab mine and tow or try it out all you want.

Enjoy Mark
smcrea
Explorer II
Feb 02, 2015
I've been asking this question all over the place. The conclusion that I'm coming to is that THEORETICALLY the 18" has more side wall so should give a sorter ride.

However I'm coming to the conclusion that this increase in sidewall is so little that it in really won't feel any different.

The differences being:
- 20" are $50 each more
- 20" looks better
Bedlam
Moderator
Feb 02, 2015
The less expensive 18" will have a taller sidewall allowing for a softer ride and the ability to air down more in tough terrain. The more expensive 20" will have a shorter sidewall allowing for better cornering and less sidewall flex at full load. Since both offer the same weight rating, it is up to you to decide on what ride characteristics you want at what price.
JIMNLIN
Explorer III
Feb 02, 2015
I looked on the Michelin Website and it looks like here's the two options:

- LT 275/70R x 18E Max load 3640Ib @ 80
- LT 275/65R x 20E Max load 3750Ib @ 80

On paper it says that the 20" can handle more load.

Its been mentioned before but Fleet Ford Specs show the 18" and 20" Wheels both have a 3590 lb rating so no weight capacity advantage above that number ....... just more tire reserve cushion.
blt2ski
Moderator
Feb 02, 2015
To me, ANY tire with a 75 or less profile tread to sidewall height is a low profile tire. You can get 50 and 55 series tires that are upwards of 35-38' with 22 and 24" rims on semi's. Those are still low profile tires due to the 50-55% of the tread width in sidewall height!

There are positives to an equal height lower profile vs higher profile tire. ie say a 265-75-16 vs a 265-70-17 tire. Both the same overall diam, same revs per mile etc.....

At the end of the day, it in reality is up to you as to which will serve you better.

Marty
smcrea
Explorer II
Feb 02, 2015
I'm like a pendulum swinging backwards and forewords with my decision on if I should get the 18" or the 20" on my new F350 SRW.

After spending most of last week on the 18" side I spoke to a guy this weekend who convinced me to go 20"

From one I'm getting, it seems that there is actually very little difference in the two.

- With 20" we are NOT talking Low Pro tires.. in fact the fall is only about 0.5" shorter

- Width is the same

I have until Wednesday at the latest to make up my mind and place the order for the truck. (I have a time constraint)

If I went 20" would anyone shout NO DON'T DO IT!!!!!
goducks10
Explorer
Jan 28, 2015
monkey44 wrote:
OK, so if we decide to go with BFG AT 275 (or even 285) do we have to change wheels too, or will stock wheels fit these upsize tires.

265 General tires came on our 2015 Chev 2500 -- Don't like the tire or the ride, so been thinking to go with the BFG 275 or 285 ... but don't want to buy wheels too if I can help it. Then again, DO NOT want to be unsafe with wheel that should not have the 275/285 on it ...

I've ridden on BFG for most all my truck life --

Any advice? Thanks

If you stay with 70 series then you should be fine with 275-285. Go to http://www.tirerack.com/tires/TRSelectAutoMakeAndYear.jsp?s_kwcid=AL!3756!3!50931993373!e!!g!!tire%20rack&ef_id=VMPsVAAAAFISrzHW:20150128161426:s and select your truck then look at tires. The rim width will be shown for each tire.
monkey44
Nomad II
Jan 28, 2015
OK, so if we decide to go with BFG AT 275 (or even 285) do we have to change wheels too, or will stock wheels fit these upsize tires.

265 General tires came on our 2015 Chev 2500 -- Don't like the tire or the ride, so been thinking to go with the BFG 275 or 285 ... but don't want to buy wheels too if I can help it. Then again, DO NOT want to be unsafe with wheel that should not have the 275/285 on it ...

I've ridden on BFG for most all my truck life --

Any advice? Thanks
4x4ord
Explorer III
Jan 27, 2015
The nicest riding vehicle I have ever been in was a 2007 Yukon Denali. It had 20" wheels. The way the tire size works is this:

The 275/65 r20 wheels have a width of 275 mm The height of the tire from top of the rim to top of the tread is 65% of the width so 178.75 mm or 7.04" this means the tire has an overall height of 34.1"

The 275/70 R18 works out to 33.2" overall height with a profile height of 7.58"

I find my 2011 F350 SRW to be very stable while pulling and I wouldn't be surprised to learn at least part of that is coming from the 20" wheels.