airagone Report post Posted March 22, 2019 Shopping for drive tires, 38 ft Newmar, originals are 275/70R22.5 - very few to choose from at this size. So has anyone upped the size to a 275/80 with good results? Southern travel only so no snow. Thanks all Share this post Link to post Share on other sites
bm02tj Report post Posted March 22, 2019 If you are fair weather only ignore this I just installed last spring conti hybrid hd3 tires in that size as a drive tire 80mph and traction tire one day I will get to use in snow Share this post Link to post Share on other sites
rayin Report post Posted March 22, 2019 I have Sailun 275/70R22.5 LR H truck tires on our MH. They are all position tires that are very quiet-running, track well, and although I never drive in snow or muddy conditions they have good traction when parking on wet grass. Sailun has some open tread designs that you may like better. I bought from a local tire shop instead of online, the total bill was $1,380 for 6 tires mounted, balanced and installed in Aug 2018. Share this post Link to post Share on other sites
richard5933 Report post Posted March 22, 2019 Have you checked with Newmar to be certain that the larger tire size isn't going to cause a problem? Sometime a larger tire looks good standing still, but it still creates a problem as the suspension moves to full travel. Wouldn't hurt to make a phone call. Share this post Link to post Share on other sites
alflorida Report post Posted March 27, 2019 Have you checked the On 3/21/2019 at 8:27 PM, airagone said: Shopping for drive tires, 38 ft Newmar, originals are 275/70R22.5 - very few to choose from at this size. So has anyone upped the size to a 275/80 with good results? Southern travel only so no snow. Thanks all If both tires are load range "G" are you sure there is an increase in load capacity? Have you look online for the diameter of the tires? If the 275/80 is much larger it could rub on something. Especially the steer tires. Share this post Link to post Share on other sites
manholt Report post Posted March 27, 2019 I would give Newmar Tech a call before changing from 70 to 80! Share this post Link to post Share on other sites
five Report post Posted March 28, 2019 12 hours ago, manholt said: I would give Newmar Tech a call before changing from 70 to 80! Same here. I'm very hesitant to change anything the factory has installed. They used that particular size for a reason. Share this post Link to post Share on other sites
wildebill308 Report post Posted March 28, 2019 I realey don't see that big of a problem. The 275/80 is 1.1 inch taller. It also turns 14 rpm less in a mile. This is handey for comparing tires https://tiresize.com/comparison/ Bill Share this post Link to post Share on other sites
richard5933 Report post Posted March 28, 2019 Like I mentioned earlier, often it's not possible to see the problem with the coach standing still. Hit a pothole or large bump with the wheels turned all the way to one side and suddenly you might find the problem. This is not a cheap vehicle, and I'd hate to have to pay a repair bill because the tire hit something mechanical unexpectedly. Or worse, have the tire blow and cause an accident. Sounds extreme, I know, but the engineers design clearance for wheel travel for the size they intend to be mounted on the coach. I've got a similar situation on our coach - it came to us with 315/80R22.5 tires. Really nice tires. They are often chosen as the metric equivalent to the 12R22.5 tires that came on the coach when the coach was manufactured. Problem is that the 315s are about 1/2" wider than the 12R22.5 and at full turn it's possible for the tire inside the turn to make slight contact with the air bag. If I should hit a bump during this time the tire could possibly do damage to the airbag. I'm going to switch back to the proper size 12R22.5 to avoid this from happening. I wouldn't switch tire size until it was confirmed from the manufacturer that it will be safe. Share this post Link to post Share on other sites
wildebill308 Report post Posted March 28, 2019 24 minutes ago, richard5933 said: Like I mentioned earlier, often it's not possible to see the problem with the coach standing still. Hit a pothole or large bump with the wheels turned all the way to one side and suddenly you might find the problem. This is not a cheap vehicle, and I'd hate to have to pay a repair bill because the tire hit something mechanical unexpectedly. Or worse, have the tire blow and cause an accident. Sounds extreme, I know, but the engineers design clearance for wheel travel for the size they intend to be mounted on the coach. I've got a similar situation on our coach - it came to us with 315/80R22.5 tires. Really nice tires. They are often chosen as the metric equivalent to the 12R22.5 tires that came on the coach when the coach was manufactured. Problem is that the 315s are about 1/2" wider than the 12R22.5 and at full turn it's possible for the tire inside the turn to make slight contact with the air bag. If I should hit a bump during this time the tire could possibly do damage to the airbag. I'm going to switch back to the proper size 12R22.5 to avoid this from happening. I wouldn't switch tire size until it was confirmed from the manufacturer that it will be safe. That is amazing. I would bet if you measure the difference between the major manufactuers for this tire the differences in diameter will be more than 1.1inch. Why don't you adjust the stop in your steering so it can't hit the airbag? Bill Share this post Link to post Share on other sites
manholt Report post Posted March 28, 2019 Bill, could be that he only has a 50 degree turn radius to begin with. My 1973 coach had a 50 and I had to back up a lot to make turns, especially in campgrounds! Wow, what a difference, when we got a 55 degree! Share this post Link to post Share on other sites
richard5933 Report post Posted March 28, 2019 8 hours ago, WILDEBILL308 said: That is amazing. I would bet if you measure the difference between the major manufactuers for this tire the differences in diameter will be more than 1.1inch. Why don't you adjust the stop in your steering so it can't hit the airbag? Bill We've had this conversation in another thread and I don't want to take focus from the original topic. Bottom line for me is that sometimes the best tire for a coach is the one the engineers and designers built it for. I investigated your suggestion, and it quickly became similar to that little old lady who swallowed a fly. I only brought this up as an example of what can go wrong when tire sizes are changed. Someone put these tires on my coach without doing a thorough investigation into the situation, and the result is tires that make contact with the airbags. Lesson? Important to do thorough research and not just assume they'll fit. Also, the fact that not all manufacturers stick with the 'standard' dimensions for tire sizes is another reason why a consumer needs to do thorough research. I set up a spreadsheet for all the possible replacement tires for my coach, and you are correct about the variances in sizing. Setting up a spreadsheet allowed me to look at all the dimensions side-by-side and eliminate a couple of tire options since their sizing was different enough to not work for me. Share this post Link to post Share on other sites
