Later years Roadtrek aluminum wheel specs

[booster]

For a long time I had wondered about and looked for specs on the later years version of the aluminum wheels for the Chevies.


I ran across an ebay listing today for the wheels and it has a spec sticker also, so now we know.


They are -6mm offset so not the same as the sock +28mm or even close to, just like the previous version AR wheel. There are several discussions on the forum on the downsides of wrong offset.


This is the wheel design being mentioned





And the spec sticker

[rowiebowie]

Always opening a can of worms, aren't you booster.

Should I distrurb my blissful ignorance and explore the offset of the Alcoa aluminum rims on my Airstream Avenue? Wonder where I would even look? Should it be stamped somewhere on the rim itself?

[booster]

Originally Posted by rowiebowie

Always opening a can of worms, aren't you booster.

Should I distrurb my blissful ignorance and explore the offset of the Alcoa aluminum rims on my Airstream Avenue? Wonder where I would even look? Should it be stamped somewhere on the rim itself?

Many, but not all, wheels will have load rating and offset stamper or cast in on the inner area of the rim. Maybe a part number and size also. It is the best place to look. If no numbers then a search by appearance and application would next to do. Almost all the aluminum wheels we have found for this application are zero or negative offset, especially if you want to get to 7.0 inches wide or more so you can go up in tire size. OEM wheels are 16X6.5" with +28 offset.


These wheel worms have been out of the can for years on the forum, but infomation still trickles in on it.

[wny-pat]

IMHO, for what it is worth, wrong offsets can cause wheel bearings to wear out early and can cause tires to rub and cause problems with your suspension, brakes, and even body parts, like fenders.

[mkguitar]

Just after I went through new tire search for my Chev based van in May- a neighbor had a dandy looking set of wheels off his GMC Sierra 4x4 2500- load rating and correct offset--- I was tempted, they looked nice and were cheap--- and maybe less unsprung weight



But I'd just had the new tires mounted up and got over it.


there are some nice wheels options available off other GM models


Mike

[rowiebowie]

Originally Posted by rowiebowie

Always opening a can of worms, aren't you booster.

Should I distrurb my blissful ignorance and explore the offset of the Alcoa aluminum rims on my Airstream Avenue? Wonder where I would even look? Should it be stamped somewhere on the rim itself?

Ok, I had some time on my hands today. From what I found on the internet about how to determine wheel offset, my Alcoa rims are approximately +30mm. This is only an approximate since I measured the rims on the vehicle and could be several mm's off one direction or the other. But I could very well be at the recommended +28mm offset (or so close I no longer need to worry about it).

[booster]

Originally Posted by rowiebowie

Ok, I had some time on my hands today. From what I found on the internet about how to determine wheel offset, my Alcoa rims are approximately +30mm. This is only an approximate since I measured the rims on the vehicle and could be several mm's off one direction or the other. But I could very well be at the recommended +28mm offset (or so close I no longer need to worry about it).

Did they have part number of or style number on them, usually on the inside of the rim somewhere, often with load capacity also?


If they are 30 that is plenty close enough and no issue. They may also be 34mm which IIRC was a pretty popular GM truck offset with the pickups.


I remember looking at Alcoa wheels when all this came down all the years ago, but didn't find any then, but it is also notoriously hard to find all the different wheels out there.


Measuring the rim width and offset on wheels with thick rim edges like most aluminum truck wheels have can be challenging with the tire still on the rim.

[booster]

I think this is the wheel on Rowiebowie's van per his pic.


https://www.southwestwheel.com/p-5242-167041.aspx


They list it at .250 offset, which would be about +6mm so would be similar to others for older pickups and trailers.

[rowiebowie]

Originally Posted by booster

I think this is the wheel on Rowiebowie's van per his pic.


https://www.southwestwheel.com/p-5242-167041.aspx


They list it at .250 offset, which would be about +6mm so would be similar to others for older pickups and trailers.

That certainly looks like my wheel. I'm surprised at the reasonable price.

I see what you're saying that they list it as a .250" offset. I know my measurements were suspect since I took them with the wheels on, but if true, I wasn't as close as I thought because I estimated slightly over 1" offset (30mm).

I guess that's why SpaceX never responded to my job application.

[booster]

As I mentioned earlier, measuring offset is tough on the aluminum wheels with thick bead lips, gets harder when the tire is on wheel, and even tougher when the wheel is still on the vehicle, so you really didn't stand a chance, I think


Part of the problem is often the instructions and diagrams for measuring the wheels as they often will show offset, backspace and wheel width all to the same point of the rim of the wheel. On most specs from manufacturers this is not how they do it, especially on the aluminum wheels because all three of those dimensions are used for different things.


Wheel width is a kind of mythical thing that is related to a point on the wheel that is considered to locate the tire bead to the wheel. It is on the inside of the outer edge of the rim. It is used to determine what tire size can be put on that wheel.



Backspace is used mostly for determining is a wheel change is going to hit on the the inner fenders when doing a wheel swap as it locates the wheel and tire position in relation to the fender. It is historically measured to the outside of the wheel on the inside lip so not in the same place as the rim width is. With a thick rim wheel, the backspace isn't as useful because if the wheels have different lip width the tire won't change exactly the same as the wheel back edge does. Most don't worry about it because hitting is rarely cut that close where it would make a difference in the real world.


Offset is the big one in the real world as it determines where the wheel and tire sit in relation to hub and suspension. Changing offset can affect handling and bearing loads as it changes the geometry of the steering. Offset doesn't matter where you measure on the rim, though, which makes it easier to measure fairly accurately if the wheel is off the car even with a tire on it. Offset is really only the dimension from the center line of the tire and outside edges of the wheel compared to mounting flange of of the wheel where it contacts the wheel hub. Tires and wheels are generally very symmetrical, with the minor possibility of raised lettering on one side of the tire sometimes. To measure the offset of the tire and wheel assembly, take it off the vehicle, lay it with the inside edge of the tire down on a flat floor, take tape measure and measure from the inside edge of the mounting flange (it is on the underside of the wheel) through the center hole. Flip the setup over and do the same measurement, but now the mounting surface will be facing up. Subtract the second measurement from the first measurement and divide by 2. This will be the offset. Positive means the tire centerline is inside of mounting flange, negative is means it is outside and will move the tires outward on the van.


Life was a lot easier with the steel wheels that had thin outer lips and center mounting sections. On aluminum wheels you can easily be 1/2" off if you pick the wrong spots to measure to.

[Peder_y2k]

I'd be concerened about aftermarket wheel strength. I know forged aluminum wheels such as Alcoa and Mercedes are strongest, even stronger than steel, but cast aluminum wheels are softer and weakest and much cheaper. Where load carrying capacity is important, choose wisely.

[booster]

Originally Posted by Peder_y2k

I'd be concerened about aftermarket wheel strength. I know forged aluminum wheels such as Alcoa and Mercedes are strongest, even stronger than steel, but cast aluminum wheels are softer and weakest and much cheaper. Where load carrying capacity is important, choose wisely.

Yep, and that is one of the things that has kept wheel selection to a very low number on the vans as you need at least the load capacity of the rear tires which for most Chevies is 6080# axle, 3040# wheel. Hopefully rowiebowie will be able to get a look at his off the van and see what the say on them, which normally would be there, including load capacity.