quote:

Originally posted by MWrench:
The Data tags shown for tire sizes were for med lab vehicles, the bottom data tag is for Bill NY conversion, these are not representative in this discussion as they are not Breakaway models.

As Steve mentioned most all if not all Breakaways 33 feet and over that we know of have 22.5 wheels.

There is a Gillig Chassis 30' Breakaway that also has 22.5 wheels and this Breakaway is nearly 8,000 lbs heavier then a Spartan chassis 30' Breakaway. This Gillig chassis also has 10 lug bolt wheel mounting. 19.5 even 22.5 wheels can and do have 6 lug bolt mounting

There is no cutoff for tire sizes. Tire sizes are generally selected by vehicle weight, chassis manufacturer or specified by the end user.

---

We can see by these different configurations the Breakaway was an effort to get the customer what he wanted. Maybe the buyer wanted a coach to drive to a local park for the weekend. On the other hand customer wanted to drive to a favorite beach several hundred miles away.

---

Now the other question. Do the rear wheels on your BaRTH or some other brand have one group of nuts holding on the outside wheel with another group of nuts holding on the inside wheel? Mine BaRTH has double nuts. My dumptrucks all have had the longer studs. The longer studs hold both wheels in a nested fashion with one group of nuts on the outside only.

Most all Breakaways built on Spartan chassis uses a Budd style wheel and attachment system. Most are 6 bolt on a 8 3/4" circle. Heavier Spartan chassis or those used with air drum brakes used a 10 bolt system and larger wheels. The Gillig chassis generally used a 10 bolt attachment system particularly when air suspension was used, Gillig chassis are usually heavier than Spartan chassis, necessitating larger wheels/tires

The BIG down side to the 6 bolt Budd system is with aluminum wheels is cracking from the lug bolt hole the hand hole caused by idiots at tire shops who use impact wrenches. Torque spec for 6 bolt system is 450-600 lb/ft.

I wanted to go to 245R70 19.5 tires on my Breakaway but the aluminum wheels were only 6" wide, not approved for 245 tires. No available aluminum wheels for the older Budd 6 bolt pattern wider than 6" are available so I had 6 steel wheels made that are 7" wide. Being steel that ended the cracking problem. ALSO 245R70 19.5 tires are over 1" larger in diameter than 225R70 19.5 very close to the original 8R19.5 tires. At 65 MPH 225R tires engine RPM was 75 RPM higher than 8R19.5 or 245R70 tires.

Tire size (22.5")on the longer heavier early Breakaways caused another issue. With the 230 HP Cummins 5.9L/Allison 6 speed and questionable rear end ratio was the root cause of sluggish acceleration and almost impossible use of 6th gear. With this arrangement the transmission would not shift into 6th gear until ~70 MPH. Further many with the 6 speed Allison the trams TCU was programmed to never use 6th gear effectively making it a 5 speed transmission!

My 30' Breakaway with 230 HP Cummins, 6 speed Allison/4.1:1 rear gears, shifts into 6th at 58 MPH engine speed 1850 RPM
@ 65 MPH.

Thanks for way more information than I imagined.

quote:

tire shops who use impact wrenches

Your information makes it even harder to trust a tire shop using impact wrenches. I change my own snow tires and always finish tightening lug nuts by hand.

---

Do BaRTH Breakaways have the two nuts per stud on the rear wheels? Is this characteristic of a Gillig chassis only?

The Budd system is industry standard, inner wheel mounted to the axle lug bolt 3/4" by a large long retaining nut sleeve with a 1" drive head, outer wheel goes on and is retained by a 1 1/2 nut threaded onto the aforementioned inner nut sleeve. Pictures up later.


I am not sure what system Gillig uses. The Budd system is a stud piloting system and therefore requires high torque to keep the wheel centered on the axle.

quote:

Originally posted by MWrench:
The Budd system is industry standard....

---

Good, because I was thinking this was only on my motor home. I have always been concerned about torque specifications on the wheels with the double nut system. Is there a torque specification with higher torque for the inside nut as compared to the outside nut? I did purchase the square nut socket for the inside nut and a few extra nuts from Commercial Truck And Trailer. CTT is listed on the Family Motor Coach Association website also for coach repair.

Inside nut sleeve (inner wheel retainer) and outside nut (outer wheel retainer) are torqued to same value. Same torque for the single nut on the front wheels. I had a table listing torque for all wheel nut applications but can't find it.

Also the 6 bolt system uses left hand thread for the left side tire mounting. Common to see stripped lug bolts on the left side of the vehicle. I am not sure if Gillig 10 bolt system is also this way. Inner stud bolt and inner nut sleeve is usually marked on the end if they are left hand thread.