View Full Version : Does 4 tenths of an inch really make a difference
10-27-2001, 12:05 AM
I have read may post on various BB about the pros & cons of 19.5" wheels verses 16". While reseaching different tire brands for replacement on the Bounder, I was amazed to learn that the big difference between the 19.5" and 16" was a whopping 4 tenths of an inch in diameter,( at the least and 1.1" at the largest), load capacity is very simular when comparing same load range (D to D, E to E, F to F). I will be replacing the front tires on the Bounder with new Kumho 811 series commerical tires 235 85R16's 15/32's of tread, diameter of 31.6" load range E 3042 lbs single and 2778 lbs dual. Happy trails all GB :)
94 Bounder 34J / Mazda B-2200 toad with Brake buddy braking
You must be using a different math if you think that there is only .4" difference in diameter between the 16" and the 19.5" tires. Perhaps you should come over and I'll let you measure mine. I can assure you that the difference is a lot more than that. And the measurement you are talking about is the inside diameter. Then when you add the fact that the tire height is greater, ..........
But why this post in the first place?
Good travel~! .......................Kirk
Good travelin! ......Kirk
10-28-2001, 07:03 PM
Well Krik, I use old math went to school in the 50's, but I didn't use any math, just looked up the specs of many tire mfgs. and they list the diameter, tread depth, load rating etc.
The reason for the post is: 1, as I stated have heard many time about the little 16" and how great the 19.5" is and 2, to get folks thinking and joining in.
Happy trails GB :)
PS: think I'll measure a couple of wheel this winter when I gots nothing else to do.
10-28-2001, 09:19 PM
Haven't had any experence with the M/H tire size but, even .4, on the rear, will change the rear axle ratio a little. Probably want matter on the front other than loosing a little ground clearance. I do know that on cars there is very little difference in total tire height on some of the different rim sizes. Some 16s will just have less tire between the rim and ground. Reason, handling, less rubber less sway.
Chelse L. Nash
11-01-2001, 08:03 PM
I'm glad that you are happy with your purchase but you didn't do your homework very well. The 16" tire has a MUCH taller sidewall than a 225 70R19.5 tire. Why you ask, does that matter? If matters because the sidewall to width ratio is bigger. This makes a the 16" tire much more prone to lateral flexing and squirm. The extra flexing increases internal tire friction thereby increasing tire heat. It requires much more air pressure to attain the same load rating. In other words, it rides harder. Besides the basic 225 70R19.5 Load Range F tire has a 20% advantage in load capacity.
I know that chassis manufacturers are a cheap bunch. They would NEVER put a 19.5" tire on when a 16" tire would do. Ford Chassis' of the early and mid '90's had 16" tires and they had PROBLEMS. No more 16" tires on CLASS A motorhomes.
Having had both I will take the 19.5 tire on a motorhome over the 16" tire everytime.
11-01-2001, 09:15 PM
Sorry to disapoint you but I did my homework, yes you are right the 16" tire has a higher sidewall, yes they may or may not have more air pressure so what. My Bounder 34' now has 54273 miles on its orginal 16" tires with not a single problem. The so called tire squirm and heating or harsh ride is no more or less then the 19.5", I have also had a Chevy with 19.5" and never again for me. My Ford and its 16" tires ride and handles sooooo much better then the P-30. Both of my F-250's had 16" tires and so does my F-350 and they handled 5th wheels and slide in campers with no problems all on 16". Another andvantage of 16" is you can get one in any town in the country but not 19.5". Ford had no tire problems till they went to the 19.5" in 99, then folks really started complaining about out of round wheel/tire controllablity etc. Happy trails GB :)
If you like 16" tires stay with them. None of us asked you to change. But that still doesn't make your 16" tire anywhere near the diameter of a 19.5" tire. But if you wish to believe that there is only .4" difference, go right ahead. for those who have any question, go to the neares dealership and measure one of each.
One question though< since we now know from you that the 16" tires are better and have as high a load rating, just why is it that all of the chassis builders for the motorhome industry are going to either 19.5" or larger tires? Do you see some great conspiracy here! Are the terrorists getting our tires?
Good travelin! ......Kirk
11-02-2001, 07:57 PM
Kirk, you have either been camping too long or are just plain losing it. I said nothing about changing to or from any size, look up the tire specs and diameters from the mgf. you just keep saying it cann't be so. Actually the mean size difference is approx 1.4" I didn't say they have higher load ratings I said load range ratings being equal they are equal. Yes the mgf have gone to 19.5" and 22.5" and yes they are made with higer load ratings and with the higher gross rigs the extra capacity is needed. No I don't think there is a conspiracy, but there is awhole lot of misunderstanding. Relax have a nice glass of ruby red grapefruit juice and check out www.goodyeartires.com nd see what it says. Happy trails GB :)
Like I asked before, why the post if you don't have a problem with larger tires?
Good travelin! ......Kirk
11-04-2001, 05:34 PM
I think Gary was just giving his opinion and I hope we all have one.<img src=icon_smile_approve.gif border=0 align=middle> I like to read all opinions and then develop my own. Then, I can blame only myself for mistakes and it keeps me busy. I thought all campers liked to share their ideas and opinions. Guess I had better find me a racing board. Don't want to offend any campers talking about my racing. Keep the post coming<img src=icon_smile_big.gif border=0 align=middle>
Chelse L. Nash
11-20-2001, 05:22 PM
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Don't know much about tire sizes but this discussion, a little more heated then necessary, has peaked my interest.
I have an 14,050 GVWR E450 based class C with 225/75R x 16E which is close to its maximum capacity at 3042lbs single (don't remember the dual limit which is lower). That tire size is the largest 16 tire you can fit on the duals on the rear and E is the highest load rating you can get on that size. So if Ford wanted to increase the GVWR, the tires couldn't take it.
When Ford up'ed the GVWR to 19,500 on the E550 thy switched to 225/70 x19.5F tires which have a maximum capacity of 3640lbs single. Why, becasue they needed an F load rated tire.
So my take is if your RV is under the D load rating, you should be on D's which only come in 16" or less, if it is within E load ratings, you should be on E's which only come in 16" or less, if you RV needs a F rated tire, get an F rated tire, which only come in 19.5 or greater. There may be some exceptions to the load ratings and sizes but looking at multiple sites, didn't find any.
Going with a higher load rating then you need will only give you a hard ride.
01 FourWinds Dutchmen 31Z
11-20-2001, 09:57 PM
Man, I remember when all we had was 670x15's!!
Chelse L. Nash
12-03-2001, 08:03 AM
I've got 22.5 on my coach. I even have a spare with the wheel on the roof. Don't know how the previos owner got that up there. Sure don't even want to think about getting it down. Ernie 84 Bluebird
05-16-2002, 03:19 PM
If you put a 19.5 wheel on a 16 rim, boy oh boy, are you gonna have problems! <img src=icon_smile_sad.gif border=0 align=middle> Have fun trying to keep it inflated, and the tire-bead won't set, I'll betcha'.
Read most of the posts here; seemed like a foolish topic to get all heated up over............
09-23-2002, 03:09 PM
Just thought that someone would like to see this again. I personnally don't have anything to add here.
09-23-2002, 11:21 PM
Try to understand one of you is talking about the rim size and the other the overall tire diameter of 2 different tires mounted on different rims (16 & 19.5).
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