Tom's RV Discus Message Board: The Airstream List Discus Message Board: Topics T - Z: Tires
By Eric Drews on Sunday, August 15, 1999 - 11:38 am:


Goodyear and Kelly Springfield make 700X15 tires. In some cases, the dealers may not have them in stock but can order them and have them in the store in a day or two.

DO NOT, I REPEAT, do not try the new trailer size tires (225-75R). I bought a trailer in Duncan Oklahoma and bought two of the "newer" sized tires. They did not fit in the wheel wells and I wound up having to get the 700X15 anyway. So, go for the right sized tires NOW. Don't settle for anything different!

Eric Drews #1047

By Bruce Levitt on Sunday, August 15, 1999 - 11:40 am:

What is the difference between the 7.00-15 tires and ST 225 / 75R15 tires and can I replace the 7.00-15 with ST 225 / 75R15 tires on my 1985 Excella or will I have a problem ??

By Joe Colao on Sunday, August 15, 1999 - 11:41 am:

Hello Bruce, We have a 1977 31' Excella. I tried the smaller tires. My trailer did not handle half as well as with our new Goodyear 7.00x15 bias tires. We bought 4 of them for $65 each, mounted, balanced and new valves. Bias tires have better sidewalls, which is desirable on a travel trailer. Radials keep more tire on the road when cornering especially at high speeds. The 7.00x15 are load range D, highway tread. The ST225/75R15 are a more aggressive thread, smaller and radials. Good luck in your choice. Joe.

By Eric Drews on Sunday, August 15, 1999 - 11:42 am:

I can't speak for all AS models, but the 225 / 75R15 would not fit in the wheel wells of my 1972 Globe Trotter. I had difficulty finding the 700X15 tires.

By Eric Drews on Sunday, August 15, 1999 - 11:42 am:

I had NO difficulty finding the 700X15s!!!!!

By Lashway on Sunday, August 15, 1999 - 11:43 am:

What is the difference between the 7.00-15 tires and ST 225 / 75R15 tires and can I replace the 7.00-15 with ST 225 / 75R15 tires on my 1985 Excella or will I have a problem ??

Yes you can.. The ST stands for something like "Special Tire" and is a designation for tires made for RV vehicles and it has heavy side walls and materials in the tire that help retard deterioration caused the suns rays. The R stands for radial however unlike passenger car radials the ST side wall construction is stronger. The 7.00-15 is generally a non radial tire or bias tire. The biggest limitation in my view is they do not have the ST "fade" resistence. However, the ST/radial is more expensive.

By Mark Hayes on Saturday, January 22, 2000 - 01:51 pm:

I have a tire question. Recently purchased 3/4 ton Ford w/460 tow vehicle. Now has, I think, 12.5/32 50R16.5, which, I understand, is really intended for offroad use, even though previous owner pulled 3 axle every day.. Going to Mexico with this thing and understand that 16.5 tires are sometimes hard to find. Should I replace these and, if so, with what. They do put a lot of rubber on the ground, but I am concerned about sidewall strength. Also need to put new tires on Airstream. Help?????

By Topdadfor3 on Saturday, January 22, 2000 - 01:52 pm:

you can get a 305-75-16 or a 285-75-16 I know dunlop makes the latter i believe brigstone makes the 305 they are both load range d or e ///////8-10 ply ratings check with your local tire dist, only problem is you will have to change rimms as well.

By Jjachter7659 on Saturday, January 22, 2000 - 01:55 pm:

One of my favorite subjects, but few listen. They think a good tire is cheap, and they think a good tire is good for 80,000 miles.

No on both counts

The noise you hear in your el cheapos (I know you paid $100 each, but their noisy because the tire company made them cheap) is because all the treadblocks are the same size, so as each one slaps the road, it makes the same noise as the one next to it. The human ear is funny, and thinks that the same noise over and over should be highlighted, and reports noise to your brain. A good tire has different size blocks, to put out a wider spectrum of sound which is not so well reported. It sounds quieter. Look at your tires. Look at the length of the treadblocks around the circumference. If they are all the same length, the tire is noisy. Better tires have varying size blocks, but they are not necessarily quiet just for that reason. If your tires wear poorly (unevenly) they could get noisy as they get older. Alignment is important.

Next Lt tires are rated for light trucks. They generally are around 2000 LB/tire load carrying capacity (it can hold 65 psi air) The same size P (passenger) tire can carry 1200 lb/tire. It can hold 36 psi of air

My suburban weighs 5250 lbs. Our airstream weighs 5000 lb. It has a single axle. So I have 10,250 LB on 6 tires. Averaging 1708 lb/tire. In actuality, I weighed things hitched. The 2 front truck tires have 2550 LB (1225 each) the two rears have 3100 lbs (1550 each) and the trailer has 4600 LB on two tires (2300 LB/tire!). Do you really want tires that can hold 1200 LB?

tires don't effect ride much. A little maybe. The lower profile tires (65 series versus 85(taller)) ride rougher. Shocks and springs effect ride. A single tube, Decarbon type (Bilstein, KYB, Edelbrock) will ride better. New springs can get a lot of ride back too. Flabby springs do not behave properly. There are other gas shocks (Monroe, gabriel, rancho etc.) that have a gas bag in them. They are junk. The decarbon type runs at 125 psi, with nitrogen behind a piston. The other type usually uses a gas bag, which ruptures with use. the gas pressure keeps the oil in the shock from foaming, and doing its job. Foam does not absorb shock.

What brands
Michelin truck tires (the commercial ones) are good, other big names are good. BUT Look at the load rating. Look at the air pressure max rating. Look at the tread blocks. It is all right their. Oh, also. The yoyo's working at the tire store, as a rule don't know nothing (s**t).

Lastly a tire is under your truck to grip the road. If it does not grip, it is not doing its job. Grip requires friction. A tire that is hard, and lasts 80,000 miles has a low coefficient of friction. So you have less traction. Did you ever see anybody advertise a tire with less traction? They won't sell. So they call them long life or green tires. Green because they improve MPG, burning less gas because they have less traction. They slide easier. or roll easier.

Something few people know. A tire turns your car or truck. To do this, it must push sideways against the road, to accelerate the front of the vehicle sideways (stay with me now) When the tire is rolling straight ahead, their is no sideways force because they are parrallel. The tire must SLIP sideways to start forcing the front of the vehicle around( it happens when you turn the wheel). This is called the slip angle (the difference between the road and the tires angle) A tire with less traction, will generally have a higher slip angle. Is this what you want when taking your 11,000 LB load into a corner? Softer tires do more work , but give up their rubber in rough proportion to the work. The best tires I ever owned lasted 3500 miles. The candle that burns the brightest lives the shortest life

ps, I am an engineer. Can you tell?

By Dave & Marilyn Wanamaker on Saturday, January 22, 2000 - 01:57 pm:

Your information on tires is excellant! I think that maybe I did the right thing this summer when I installed Michelin LT 215 75R 15's on our Safari Van as we were getting ready to tow our recently aquired Airstream. The Airstream dealer recommended these tires but I had to argue with the tire dealer as he felt(strongly) that I should be installing passenger rated tires. I have been very happy with them so far. My question is, now that I am not towing again until spring; what air pressure should I be running. Should it be 35psi as in a passenger tire or 40psi or more as they are LT tires? I look forward to your comments,
Dave Wanamaker