Replace skinny P30 front wheels

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T

Taxman

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Nov 23, 2006
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My first post on this forum.  By way of introduction, my wife and I recently purchased a 1990 33' Airstream Land Yacht.  The coach is in excellent condition, however the P30 chassis needed some serious upgrades to bring it up to snuff:  Super Steer bell cranks, Roadmaster front sway bar and rear sway bar bushing kit, Bilsteins all around, Banks PowerPack and a Gear Vendors.

Needless to say, we are most pleased with the results thus far.  The MH is much more stable, has a more comfortable ride and the Banks/GV combo is dynamite! 

HST, though, I need some information and advice, please.

I need new tires, and am interested in replacing the skinny 6" front wheels with wider (preferrably 7.5") wheels to take advantage of the low profile tires now available.

So far, I have been unable to locate 7.5" x 19.5 wheels which will fit a P30 chassis.

Do any of you more experienced motorhomers know where I might be able to purchase a pair of them at a reasonable price?

I'll leave the drive and tag axles wheels as they are, and replace those tires with "stock" 8R 19.5s.

While we are talking wheels/tires, what brand tires would you recommend?

Also, I am interested in increasing my front track a couple of inches. Anyone know of a safe, effective way to do that?

Thanks in advance for you advice and comments.  I appreciate this forum -- I learned a great deal about motorhomes and RVEEing in the months before I purchased my LY, and look forward to learning even more as time goes on.

 
Hi Taxman,
Welcome to the RV Forum.

I suggest you don't attempt to change the track by anywhere near that amount. You're talking about MAJOR changes in steering and suspension geometry if you try to move the spindles out. One thing racers sometimes do is to place spacers between the wheel and hub, but 1/2" per side is about maximum. You may also have clearance problems with bodywork, especially during turns or when driving over roads where the chassis is moving up and down a lot.

What size tires are on it now, and why do you want to go to a low profile tire and 7-1/2" rims? Did you have a particular tire size in mind? You might get a bigger contact patch, but that's not always a good thing. 
 
The P30 is already a relatively wide track for the body and I see little advantage and lots of disadvantages (as Karl notes) to changing it. Messing with the front end geometry is rarely a good idea.  Nor do I see any reason to change the tires to low profile models, especially just the fronts. It's a motorhome, not a street machine.  ;) 

What are you trying to achieve with these proposed changes?

 
Thank you, RV Roamer.  It is good to be here and be able to explore ideas.

I hadn't thought about moving the spindles -- was thinking more about wheel offset.  It appears that the front wheels have a negative offset, and I thought that, in conjunction with new tires, if I could get 7.5" wheels with, say, one or two inches less negative offset, I'd effectively have a wider track.

My objective with low profile tires and a wider front track is to obtain a smoother ride and more stability.  My reasoning was the same as with my car -- wider tires = better handling and better ride. 

Plus, there is the appearance factor -- wider tires/wheels (within manuvering limitations, of course) that fill up the wheel well look better, IMHO.

I may be way off base on my presumptions about the relationship between auto suspension/tires and RV suspension/tires, however, and that is the beauty of forums like this.  If I am way off base, someone is likely to call me on it and save me a bunch of money and grief!

Thank you for your comments.
 
Karl,  please see my response to RVRoamer.

Looking for better handling and better looks.

Thank you for your response.
 
Thanks, Kurt.  It appears that only used Boxer Wheels are available -- company is out of business.  I'll keep my eyes open.
 
Low profile tires do not inherently provide better ride or better handling. It's mostly myth. Really low profile tires, e.g. 50 or 60 profile, have much poorer ride because there is so little sidewall to flex and absorb impacts.  Lowering the entire rig gives a slightly lower center of gravity, which may help handling some, but lowering the front only is going to be meaningless, I think.

As for whether it looks better, it's your coach and your $$$
 
Thanks, Gary.  May not be doable anyway -- I have not found any 7.5 x 19.5 wheels with the proper offset (roughly 4").  I think that if I can find the proper wheels, 245/70 R19.5 tires on the front would provide a better ride than the 8R19.5s, and I believe they would also measureably improve the coach's road manners.  I could be wrong -- just trying to ponder the whole deal out and get some help from the forum.  BTW, in any event, I'm sticking with the 8Rs in the rear.  Wider wheels all around is definitely not $doable$!

I've set the coach up fairly well, I believe:  Banks, Gear Vendors, Bilsteins, Super Steer bell cranks, Roadmaster sway bar kit and Safe Steer.  Super Steer panhard rod will not fit because of the tag axle, dagnabbit!

Just looking for a little more before the Great Adventure begins this summer!
 
IMHO:  It's not that big of an issue:  I have the Ellis Safewide Wheels on my coach, and absolutely love them.  You go from skinny tires on 90 - 100 psi of air (hard, transfer all road harshness into the chassis) to much wider track tires riding on 50 psi of air.  (Softer, absorb bumps, wider track, more stability)

Like you, I added many of the options you list on your coach.  The monotube KYB shocks and Safewide Wheels were among the best investments made.

Regardless of the fact that Boxer Wheels is now out of business, I'd submit that locating a used pair and giving them a try would be worth the investment and/or risk...you need not give up on your desire for improved ride and increased track.

Again, I speak only from my personal experience on my coach.  For what it's worth.
 
Thanks, Kurt.  I'll certainly investigate that possibility.  What size tires are on your wheels?
 
If I recall, they are 31 X 12.5 X 16.5.  Pretty wide...that's for sure.

I also remember some detractors in Motorhome articles from years back, stating concerns over increased overhung load on the bearings and spindles.  All I can tell you is that after 20,000 miles or so on mine, I would do it again in a heartbeat.

You have to consider that it may drop the front end of your coach by about 1/2 - 1 inches, and measure for clearance of the wider tires within your coach bodywork.  I had to cut off a step to my drivers door which hung down in front of the tire, but a non-issue considering the improvement in ride quality.

Ellis Safewide used to advertise that these wheels would make your rig float down the road relative to the skinny bicycle tires as OEM equipment.  I would agree as far as my experience goes.

 
Kurt is right that lower tire pressures can smooth the ride, but the required psi used in the tire is related to the size of the contact patch, not the sidewall profile. A wider tire generally increases the contact patch, regardless of profile.  Check the tire inflation table for any tire size you are considering.
 
Kurt & Gary,

Thanks for the input and info.  Since "retiring" is a critical and relatively large investment and has long-term safety, comfort and handling implications, I want to do it right.  Fortunately, I am not under a huge time constraint and can keep exploring the alternatives.

Thanks again.

FRank
 
Thanks, Gary.  I got real lucky when I purchased this coach in November, and I do not want to screw it up by buying a set of tires in haste.  They have to work well for me and last a long time -- the Mrs. and I plan to wearem out over the next four or five years!
 
They have to work well for me and last a long time -- the Mrs. and I plan to wearem out over the next four or five years!
Click to expand...
Tires on an RV will wear out even if you don't drive 'em to death. If you haven't already done so, I suggest you click on the "LIBRARY" button above and check out the article on tire replacement under the "Maintenance Items" topic. Don't know how old your tires are, but check the date codes as soon as you can.
 
One of your first concerns on this chassis should be to get it weighed (with as much of your normal travel load on board as possible) and then to make sure the front air bags and tires are inflated properly for the actual load. The psi in both places contributes greatly to both handling and ride comfort. In general less psi equals more comfort and "softer" handling, but the range is fairly broad and you have already stiffened up the front considerably with your other enhancements (all well chosen, by the way). 

I'll grant that the stock tires on older P30's do look awful skinny, but I seldom hear of any big improvements attributed to changing tires. Maybe you can find a wider tire that will at least look better.  The P series RV chassis is a derivative of a Chevy medium truck (actually that of a delivery-type step-van, so maybe there are tires & wheels listed for trucks that would fit? Also, Workhorse upgraded the chassis considerably after they took it over around 1999 and I would think that there would be parts available for later models that could be retrofitted to yours. I know they developed a new air bag that is backward compatible and I think they widened the track as well. 

There are two shops with considerable expertise in your chassis, both in the Northwest. One is Henderson's Line Up and the other is Eroc's Performance RV.  You might want to contact them about your wants and needs. Henderson's does an excellent and professional suspension perfromance evaluation that is well worth the time & money if you want to get things right.
 
Karl, Gary

Thank you for your insight.  I appreciate your expertise and taking the time to offer your (well thought out) advice to me.  I'll certainly take it into account as I move forward with my "retiring" effort.

Happy Trails,

FRank
 
  You had a question about wider wheels on the front of your motorhome. I have a Class A 1992 holiday rambler imperial, 37 footer GAS ,10 LUG Ford chassis. A few years back i had a machine shop in Elverson, Pa. make me 10 inch wide front wheels and "WOW"did it make difference in the way it rode. Your best option is to find a machine shop that will build you these wheels.
 
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