How To Get Bigger Tires For Sunrader

[purplhay]

Looking for advice on doing a tire conversion from dually to single..

After just doing over 175 miles of serious washboard in Idaho backcountry, I am now considering trying to put bigger tires on this rig. I'll be doing about 10 MPH or less in order to prevent shaking this rig apart while a Dodge 2500 diesel flies by towing two trailers, one a 25'er with another trailer of two ATV's behind him. His trailers are shaking but the truck just flies by leaving me in the dust. My rig with little 14" tires just happens to fit perfectly in those washboards and just wants to tear this rig apart.

If I could increase tire diameter and convert to single tires, that gives me the option to air down when hitting the washboard. When I get back to pavement, air up for safe travel. The air down plus larger diameter will allow me to roll a bit faster over the washboard. Even if I could up my speed to 20 MPH without shaking apart, that would double my travel time in the back country.

I would be faced with the following to do this conversion;

1. custom wheels 5 total, 4 in use and one spare. Get custom steel wheels with same lug pattern, same offset for one side of wheel, plus 1 or 2 inches other side.

2. rear lift (already done, it was easy, beefier leaf springs, added about 3 in).

3. front end lift (2-3 inches),

4. rear end gear reduction. I already have the full float rear end but will need to reduce the gearing to compensate for the tire diameters.

5. front flares to account for the wider front tires. Some fender trimming may be necessary too.

Do all of above so that I can select a common D load rated tire. All valve stems accessable for easy air up and down. The front tires will get wider and the rears will essentially get less tire patch (from dually to single) but still maintain the width stability.

I considered a 4WD conversion but don't beleive the 4WD will help. This thing as it is goes just about anywhere within reason. So much weight on the rear tires, it never loses traction. Plus I have a winch if I ever can't roll over something or get stuck.

What's wrong with my assessment? Is this possible? The rear end gear reduction or the front lift may be my biggest hurdles? Please any and all insight will be appreciated. Throw in estimated cost too since that is a major factor. I want to do this now since my tires need replacing. I got about 20,000 out of a new set, btw.

Greg from Boise.

[linda s]

These guys can make your wheels. They make same bolt pattern for military pull trucks. Also fit Dodge power wagons and older Ford trucks.

http://www.mrt-wheels.com/

Front wheels are a different issue. I don't have front wheels with adapters so I don't know what you would have to change there

Linda S

[zero]

After just doing over 175 miles of serious washboard in Idaho backcountry, I am now considering trying to put bigger tires on this rig. I'll be doing about 10 MPH or less in order to prevent shaking this rig apart while a Dodge 2500 diesel flies by towing two trailers, one a 25'er with another trailer of two ATV's behind him. His trailers are shaking but the truck just flies by leaving me in the dust. My rig with little 14" tires just happens to fit perfectly in those washboards and just wants to tear this rig apart.

My Dodge HD diesel W250 with 235/85-16" tires is absolutely awful on washboard and rough roads. Bounces all over the place if empty. Put a load on it and it's fine. But my Dodge has air-springs/bags like the Toyota. We tried to travel a back road in the Adirondacks recently and bounced so bad on the washboards - we turned around and gave up.

I seriously doubt putting bigger tires on your Toyota is goning to make it that much better. It is an overloaded mini-truck and I assume - using air-springs to hold it up. But that's just my opinion. We recently took a trip with a 1988 Toyota Minicruiser on miles and miles of washboarded roads. I either had to go real slow or real fast. It was the in-between speeds that nearly shook us to death. Not too bad if I was able to keep over 45 MPH. When I say "not too bad" I mean at least not as bad as my Dodge W250. That all being said - I can stick a truck camper on the back of my Dodge and with that extra 2000 lbs. - it rides fine. It will also get 17 MPG driving at 75 MPH with that camper and 4WD available. So if that's the kind of deal someone wants - why have a little Toyota?

If you wanted bigger tires - 27 X 9.50 X 14LTs with a 4.56 rear would keep the same engine revs per MPH as your stock 4.1 rear with the OEM 185R-14" tires.

If you wanted 33" X 15" tires - you'd need a 5.29 ratio rear to make the same engine revs per MPH as stock.

[purplhay]

Thanks for the replies. I am on springs in the rear and not on the air bags. Speeding up to reduce the washboard works for regular vehicles but a loaded minihome with all of that cantilevered weight swaying back and forth will never balance out before ripping all of the appliances out of the cabinets first.

greg

[linda s]

Your rig came with air bags. Are they broken? That might be some of your problem. Would definitely stop some of the bounce. A lot cheaper to buy replacement bags than all that other stuff.

Linda S

[WME]

Check the suspension bushings too. If they are bad the rear springs can jump around without doing any springing.

[zero]

. Speeding up to reduce the washboard works for regular vehicles but a loaded minihome with all of that cantilevered weight swaying back and forth will never balance out before ripping all of the appliances out of the cabinets first.

greg

Works with my 20 foot Toyota Minicruiser. Back roads up in the Michigan UP are washboarded more often then not.

[Derek up North]

I'm not sure I've heard of anyone who has converted a 2wd Sunrader from duals to single. (1 4wd that I can think of). So it's gong to be hard to predict if spending the big $$$ for new custom rims and a set of tires is going to solve (or even improve) your problem.

I'd be inclined to first play with what you've already go. Make sure everything is in good shape. Springs, bushings and shocks. Especially shocks. Unfortunately, I don't think there's a supplier of off the shelf adjustable shocks so a trip to a supplier of custom ($$$) shocks might be required. A set of air springs with an onboard compressor would allow you to adjust things on the fly.

I've no idea if urethane bushings would make things better or worse.

How about letting us know what you've got right now? Sunrader 18' or 21'? Shocks, springs, bushings, tires?

Lots of people say Bilsteins are the best, even claiming that their Motorhome 'handles like a sports car'. I seriously doubt this claim. But what works best for handling in terms of valving MIGHT not be the best for valving to tame washboard. That's why car manufacturers have whole departments devoted to suspension design and the results are nearly always a compromise.

[paulnptld]

I just had Bilsteins done as well as respringing my Dolphin. It made a huge difference. I also found out on a recent trip that the trick to surviving washboard is completely counterintuitive - ie, go FASTER. I was amazed at the difference this made on a lengthy stretch of gravel road in eastern Oregon a few months ago.

[purplhay]

I have 21 footer. Yokohama 185/14 d range tires.

I have new bilsteins all around. New add a leafs in the rear all gone through professionally. All bushings good, shock good etc. It drives amazing on asphalt, hardly leans in curves and feels great everywhere except washboard. I do considerable off road with ruts, dips, rocks and it is quite stable.

I need new tires now and this is why I have started this discussion to explore all of my options.

[abdiver]

If you go faster you end up skipping over those washboards and get a smoother ride.

[WME]

For info. I currently have a 26ft class A, it has 235/85/16 tire. I have to take care on washboarded roads. I have driven a Blue Bird MH with 11R22.5 tires, washboards will eat it up. You can't find a rim big enough to smooth out most washboard roads. You just need to find the magic speed, it will vary by road.

[purplhay]

that was a few months ago that I started that thread.

Update, I just received my new custom wheels today 5 total. They fit and now I need to powdercoat and order tires. I found a 245/70/16 tire that will fit and be perfect, meet all load specs and final diameter matches the gear ratio required. Since last posting, I also raised the front end by 2 inches with a aftermarket torsion bars. That with the already beefed up rear springs made this 21' Sunrader flat and level, front to rear.

My current total height of stock 14" wheels are approx. 25" total with tires. The new 16" wheels with 29.5 inch tall 3000 pound load rating tires fit in the back no problem. In the front, I will need to modify front fender well and probably add front fender flares since the tires stick out a couple inches. Better stability, worse turning radius.

Next, rear end reduced to match the tires with a slight hedge in gearing towards my favor. That with a locker rear end will be quite a good off road set-up. Who needs 4X4 when you have 4500 pounds on the rear tires. 2300# on the front tires won't help that much in a 4x4 situation very well. This and my winch will assure me mobility where ever I go.

Wash board ?? Still don't know how much better this setup will be. In theory it should be. I'll post pic's within the month.

[zero]

You'd have to put 4.88 to 1 gears in the rear to bring it back close to where it was before - in regard to pulling power and the speedo working correctly. 5.29 to 1 gears to make it run maybe a bit better then it does now. Plus it's going to sit higher with more wind resistance. Your project, your RV and obviously, your choice. I wouldn't to it. If I wanted a higher RV with bigger tires - I'd use a bigger RV.

I'll note that I have two RVs with 16" single tires and both are awful on wash-boarded roads. No better then my 1988 Minicruiser with 14" tires and duals. My 1992 Dodge-Cummins W250 4WD truck with a slide-on camper and 235/85-16" tires is one. The other is 1986 Chevy Blazer Chalet diesel with 245/75-16" tires.

I will note that the amount of air in my air-bags in back makes a big difference on wash-boarded roads with my 1988 Toyota. Last summer while on miles and miles of heavily washboarded roads in the Michigan UP - I lowered the air-pressure to 20 PSI and it made a substantial difference. I also had to drive fast. 30 MPH was awful. 45 MPH much better.

[linda s]

that was a few months ago that I started that thread.

Update, I just received my new custom wheels today 5 total. They fit and now I need to powdercoat and order tires. I found a 245/70/16 tire that will fit and be perfect, meet all load specs and final diameter matches the gear ratio required. Since last posting, I also raised the front end by 2 inches with a aftermarket torsion bars. That with the already beefed up rear springs made this 21' Sunrader flat and level, front to rear.

My current total height of stock 14" wheels are approx. 25" total with tires. The new 16" wheels with 29.5 inch tall 3000 pound load rating tires fit in the back no problem. In the front, I will need to modify front fender well and probably add front fender flares since the tires stick out a couple inches. Better stability, worse turning radius.

Next, rear end reduced to match the tires with a slight hedge in gearing towards my favor. That with a locker rear end will be quite a good off road set-up. Who needs 4X4 when you have 4500 pounds on the rear tires. 2300# on the front tires won't help that much in a 4x4 situation very well. This and my winch will assure me mobility where ever I go.

Wash board ?? Still don't know how much better this setup will be. In theory it should be. I'll post pic's within the month.

I'm sure lots of us would love to see these custom wheels and know where you got them. Please?

Linda S

[purplhay]

TIRES ON. VERDICT, rides better than I expected and looks amazing. I have to wait for the washboard verdict. It already has a very noticeable dampening affect. Rides much better small harsh abrupt feature in the road, i.e. manholes, speed bumps etc..

I'm re-naming my rig the SUNROAMER.

Next step is to ;

• pound out front fender wells, tires rub on extreme turn. no biggie.
• front flares - tires stick out.
• rear end reduction with lock out.

[Totem]

Pictures or it never happened :-)

[linda s]

Is that you telling us we can't see it or a mistake. I would really like to know who made your wheels. Others might be interested in this kind of upgrade and some 4x4 owners would probably also like to know where these wheels that fit on a full float axle came from. My friend Jerry did a Front Range full float conversion on his 4x4 Sunrader and went to 16 inch E load range tires but the lug pattern on this conversion leaves you with a stock 4x4 lug pattern so he had lots of wheel choices. I wouldn't mind having larger wheels on mine

Linda S

[purplhay]

SunRoamer 2WD.

• 2" lift front end accomplished with new beefier torsion bars.
• 2" rear lift with add a leaf.
• New gas monroe shocks
• Stock Air bags
• Full floating 1 ton rear end.
• 245/70/16 Dick Cepek Trail Country Load E #2900 tires.
• 16 X 8 custom steel wheels powder coated black with custom offsets. Reversible front to rear wheels.
• 4:88 new gears rear end with locker.
• no clearance issues for the rear.
• needed to push in floor board about an 1/2", easy, sledge hammer. slightly modify plastic fender liner.
• Will add front flares since tires protrude about 2".

Initial impression driving around town is that it has a very stout feeling. Lots of damping due to extra tire rubber. I instantly noticed the absence of abrupt shock vibrations from driving over manhole covers and other surface imperfections. Can't wait to hit the washboards.

With this setup, I have more tire patch up front and wider front stability. All of this may reduce my turning radius, but I haven't noticed. Reduced MPG due to height, maybe. I'm about 4.5" taller total. But with that height, I also have 4.5" of airflow underneath as well.

The rear wheel setup went from duellies to single tire with a minor loss of tire patch. The total tire patch contact area of all of the duellies is only 110% larger than this single wheel setup. In other words the new bigger tire on the rear is 90% of the total of tire patch compared to the stock duelly wheel setup.

No speedo changes necessary, new gearing gets me where I was before with a slight % in my favor.

[purplhay]

shows difference between 185R14 and the new 245/70/16

[linda s]

Looks great

Linda S

[Roy in Jax]

Great job on installing the new wheels. Thanks for all the updates. Who makes the wheels?

[linda s]

I know we seem very insistent about who made the wheels for you but it's very difficult to find a shop that actually makes custom wheels. Please tell us. Name and address.

Linda S

[Boy]

Nice looking set of wheels you had made. Im doing a similar setup for my 4x2 to 4x4 conversion with a 1 ton rear toyota axle. I have contacted Stockton Wheels (http://www.stocktonwheel.com/) and they quoted me just a hair over $200 each 15" wheel, forgot to asked if shipping was included. 16" is the same price but i cant locate new 6 on 5.5 bolt circle with the right offset.

I will be ordering a set of only 2 for the rear soon. A loose tire will be hauled with me along with my manual tire changer for a roadside repair.

I would greatly appreciated hearing who built yours.

[linda s]

Good to hear Stockton is doing custom Toyota wheels again. They limited their production for a while after the owner died. Looks like they are recovering

Linda S

[purplhay]

Nice looking set of wheels you had made. Im doing a similar setup for my 4x2 to 4x4 conversion with a 1 ton rear toyota axle. I have contacted Stockton Wheels (http://www.stocktonwheel.com/) and they quoted me just a hair over $200 each 15" wheel, forgot to asked if shipping was included. 16" is the same price but i cant locate new 6 on 5.5 bolt circle with the right offset.

I will be ordering a set of only 2 for the rear soon. A loose tire will be hauled with me along with my manual tire changer for a roadside repair.

I would greatly appreciated hearing who built yours.

[purplhay]

Wheels are 16 x 8 with 5.5 offset. Made by marsh racing wheels Alabama. Had them made with solid centers since nobody makes a center for these. Had centers machined for window access for valvestems. Wheels are reversable front to rear. Powdercoated black. All that plus shipping was 1200 for 5 wheels.

[linda s]

Thanks I have heard of Marsh. Nice to know a manufacturer on the east coast that does this.

Linda S

[Derek up North]

5.5" offset or backspace?

[purplhay]

My gear change plus locker will cost about the same. Driving on road is night and day difference.I hope it doesn't give me too much confidence when negotiating ruts etc. I guess that is what the winch is for.

[purplhay]

5.5" offset or backspace?

[purplhay]

I forgot which is which. 5.5 from back edge of rim to mounting surface. Keep in mind I reverse front to rears. This setup gives me same stance in rear and increases stance in front.

[Derek up North]

5.5" backspace is what you've got. 5.5" offset would be the centerline of your 8" rim being offset 5.5" from the mounting surface. So you've got about 1.5" offset (ignoring the thickness of the metal).

[purplhay]

That's right. I ended up with about 2" of rim lip on the outside. Sorry for terminology mix up. If anyone wants to Order wheels? Contact me because I did a lot research and measuring and prObably have more to say about that than not. Like you, I can't afford to make expenSive mistakes.

[Totem]

that winch is a bit light on the weight rating, be careful. My guess is that your rig weighs in at 5-6 thousand lbs. I would have put a 12,500 on it; or make sure to use a snatch block.