275/80/r22.5 vs 255/70/r22.5

[Nwatkins176]

Okay I need to replace all six tires before my next trip.  Currently on the coach there is 275/80/r22.5.  I found what I think is a good deal on 255/70/r22.5.  I know the size ratio and know these tires are about an inch narrower and probably about a 1/4inch less in diameter.  The load ratings are the same, is there any harm going to a smaller tire? 

I have a 2005 Damon Tuscany 41' DP

Here is the deal, can I beat this?

http://www.ebay.com/itm/6-Tires-Roadmaster-RM120-255-70R22-5-RV-motor-home-tire-255-70-22-5-255-70r225-/251175622616?_trksid=p5197.m1992&_trkparms=aid%3D111000%26algo%3DREC.CURRENT%26ao%3D1%26asc%3D14%26meid%3D5554899500567008952%26pid%3D100015%26prg%3D1006%26rk%3D4%26sd%3D250825567627%26

 

[captsteve]

Thats a great price but decreasing your contact patch by nearly 15% is something to think about when you are rolling 30,000 lbs down the highway in the rain and you need to stop fast.

You are basically losing 48 sq. in of contact area.

Just something to think about.

Steve

 

[Nwatkins176]

Never thought about cp with that... 

 

[Ned]

The smaller tires may not have sufficient load limit to support the axle weights of your coach.  Check your weights against the load inflation table to see if they can carry the load.  RVs are generally equipped by the manufacturer with the smallest tires that will support the weight, so downsizing is not safely possible.

 

[Gary RV_Wizard]

Double check those weight ratings - it is inconceivable to me that a 255/70 has the same rating as a 275/80. At the very least they will require much higher air pressure for the same load, making the ride harsher.

Looking at a Goodyear inflation table for those sizes, I see the max capacity of the 255/70 is about the same as the minimum for the 275/80, but the psi on the 255 is 120 vs 90 for the larger tire.  And if your axles can ever exceed 5500 lbs/tire, the 255 is inadequate anyway.

 

[Nwatkins176]

You all were 100% correct.  I was mistaken, the difference is 1500 pounds per tire, so those cheaper tire are not going to work.  I now hunting for 275 80 r22.5 tires, but those are much more expensive, but better than blowing a tire at 70 MPH.  thanks for your help

 

[silva500]

I figure I can ask this question on this thread, as it is related.  I recently acquired a 1996 American Tradition with 10 year old tires. The first order of business is new tires.  The existing tires are 255/70R22.5.  I wanted to verify the tire size, in case someone had substituted.  I checked on the sticker by the driver's window and, sure enough, the coach came with 245/75R22.5G.  This is a difference if 5.2 mm in sidewall height, and a difference of 10 mm in thread width. Although these differences do not seem to be a lot, I am inclined to follow manufacturer's recommendation.  After looking at a few sites on line, there seems to be more alternatives in the 255 tire than in the 245. Could this be a factor if you ever have to buy one on the road?  Any suggestions?

 

[captsteve]

The above posts all pertain to you also. Load ratings should not be trifled with. I would check prices on tires a little larger also you may find a popular size that will be cheaper.