Rear dual tire space - too close?

[Effy]

My 2012 ACE 29.1 came with Continental HSR 225/70/19.5. I keep PSI at the rated 85. There is easily 3/4 - 1" of space between the rear duals. These tires ride rough however and offer a lot of road noise and feedback.

The 2013 29.2 came with Goodyear G670 RV 245/70/19.5. I keep the PSI in these at the recommended 82. These ride much nicer and quieter than the smaller conti's. But the spacing on these is much closer between the duals. Like closer to 1/4 to 1/2".

Logic tells me this might be close enough for a rub at high temps and bouncing. That said we have taken it on long trips and I inspect them regularly and I can't see any evidence that they have ever rubbed. Am I being paranoid? Part of me wants to think Ford or Thor knew what they were doing when they spec'd the larger tires, but part of me also thinks I am being naive to put my faith in the RV industry for doing the right thing. Thor obviously would never openly admit to a dangerous dual gap.

Am I being paranoid? I love the tires and so far no issues, but it seems awful close. I think I could buy spacers to ease my mind but if there is no real issue why bother. It's a light coach at only 16k#.

Thoughts?

[Effy]

tderonne wrote:
Not sure exactly what F53 chassis you had and have, but this may explain the difference:

Ford Q-211 Bulletin

Thanks Tim. Good info. The new ones are G rated and on the 6.75 rims. So maybe they are good and safe based on the specs at least it's what's accurate. I may have a tire shop check them, but like I said, no evidence of rubbing and I am very diligent at maintaining proper PSI.

In the for what it's worth category, I love the Goodyears. Quiet and smooth. Amazing the difference a tire makes.

[tderonne]

Not sure exactly what F53 chassis you had and have, but this may explain the difference:

Ford Q-211 Bulletin

[Effy]

rgatijnet1 wrote:
Since the rough measurement seems to indicate that you are 1/4" too narrow, it may be a good idea to take it to a tire shop and get an accurate measurement. They would also know about tire spacers.
Barring that, then you are just a test subject to see if the tire manufacturers are right or not.

Instills me with a lot of confidence 🙂

I learned a lot here again today. Thanks all.

[rgatijnet1]

Since the rough measurement seems to indicate that you are 1/4" too narrow, it may be a good idea to take it to a tire shop and get an accurate measurement. They would also know about tire spacers.
Barring that, then you are just a test subject to see if the tire manufacturers are right or not.

[Effy]

ok, so the rims - according to the sticker are 6.75. Which is good. Minimal but good. I measured the distance from the outside edge of the tread on the inside tire to the outside edge of the tread on the outer tire and it measures 10 and 3/4". Does that mean my spacing is off by 1/4"?

Would a spacer correct this? Would there even be enough threads and room on the spindle to put a 1/4 space in? Would it be too much leverage on the outer egde of the bolts? Is it worth it? I feel a little like I am over thinking this.

[wolfe10]

Rim width is stamped on the inside of the rim-- so look at back outer wheel.

It should also be on the GVWR sticker which is usually near the driver's area.

[rgatijnet1]

Effy wrote:
So I guess it's less about the space between the tires, and more about the space between the rims, provided the tire PSI is correct. Thus ensuring adequate space between the tires. Now, how in the world to measure the distance between the rims.. I am no contorsionist.

As I said, just measure the tires. In other words, the outer edge of the tread on one tire to the exact same spot on the other tire should be close enough to give you an idea. You should be able to just lay a yardstick across the tires and measure the distance between one edge of the inner tire tread to the same spot on the outer tire tread. If it is 11" or more, you are good to go.

[Effy]

So I guess it's less about the space between the tires, and more about the space between the rims, provided the tire PSI is correct. Thus ensuring adequate space between the tires. Now, how in the world to measure the distance between the rims.. I am no contorsionist.

[rgatijnet1]

Here is a link for dual spacing. For your Continental tires, the center to center rim spacing was 10". With the Goodyear tires, the center to center rim spacing is 11".
Time to get under and measure. You should be able to get pretty close by measuring the spacing from one edge of the inner tire to the same edge on the outer tire.
Dual tire spacing

[DUNEBUGGYDOUG]

Most of rocks and other debris will come flying out from between the tires and whack whomever is following you

[rgatijnet1]

On my coach, the width of the rim is stamped on the rim itself. Naturally this means removing the wheel cover to see it, which is a little hassle. You may be able to look at the factory specs for your coach to see what size rims were supplied on the standard coach.

[wny_pat1]

Like rgatijnet1 said. The tire specs will tell you what width of rim the tires have to be on. The Conti 225/70/19.5 will fit a wheel width of 6.00" to 6.75". The GY 245/70R19.5 is spec'ed to fit a wheel width of 6.75" to 7.50". You can not put them on a different size wheel or you will have various problems. The proper air pressure using the manufacturers load / inflation charts will keep the dual tires from kissing each other.

As SeaDog/BRR pointed out, one has to be very careful to not pick up any debris, such as rocks or chunks of wood, between the dual tires. Something like that can cause a blow out of both tires in less than ten miles. Why do I say "less that 10 miles"?? Because I have had it happen. Both tires ruined. In fact, I saw the rock and was going to get it before I pulled out. 10 minutes later, I pulled out without remembering that stupid rock. I was stupider than the rock, cause I should have taken care of that the minute I saw it.

[Effy]

rgatijnet1 wrote:
Looking at the tire specs available online, the Continental tires were to go on a 6" rim and the Goodyear tires could go on a rim from 6.5"-7.5". If you have 6" rims, I would say no to the Goodyear tires.
1/4" to 1/2" seems like sufficient gap but that seems too close when you hit a bump and the coach is bouncing down the road. It is also so close that it may allow a piece of gravel, or other road debris to become wedged between the tires, which could quickly cause a sidewall failure. The dealer that installed the tires should have checked the specs regarding dual spacing.

How do I tell the size of my rims?

[rgatijnet1]

Looking at the tire specs available online, the Continental tires were to go on a 6" rim and the Goodyear tires could go on a rim from 6.5"-7.5". If you have 6" rims, I would say no to the Goodyear tires.
1/4" to 1/2" seems like sufficient gap but that seems too close when you hit a bump and the coach is bouncing down the road. It is also so close that it may allow a piece of gravel, or other road debris to become wedged between the tires, which could quickly cause a sidewall failure. The dealer that installed the tires should have checked the specs regarding dual spacing.