Single Well and double well rims

[bljnv]

For some tyres (eg: 500/70R24) we have both W16 and DW16 rims approved. What kind of effect do these rims have during the tyre assembly. What will be the effect on strength between the two design rims. Experts please advise.

 

[CapriRacer]

I was hoping some of the wheel folks would reply to this, but I'll make an attempt even though my expertise is tires.

None of the wheel contours should cause issues in mounting. That is one of the purposes of the wheel standards.

Strength? The design of the rim itself (including its strength) is independent of its contour - which is what those letters and numbers mean.

 

[bljnv]

Thanks CapriRacer for your views.
But I am sorry for not communicating the requirement properly.
When I said tyre assembly, I meant assembly of tyre over the rim and not the wheel mounting to the axle/hub. In essence, I am asking if tyre assembly over a double well rim is easier than assembling to a single well rim or it is vice versa.
Also both rims, W16L and DW16A,are acceptable as per T&RA standards. T&RA standard provide the load limits for the tires only ( for 500/70R24 IND tyre the tyre load limit is 5000 kg with 400 KPa inflation pressure) with a rider that loads should not exceed rim manufacturers recommendations. Though both single and double well rim should technically take the load, which will stand better in terms of fatigue life.

 

[MikeHalloran]

I do not work in the tire and rim industry, but I suspect the double well rims exist to ease mounting very wide tires.

Both have to meet the same standards.

I'd be surprised to see much difference in 'strength', whatever you mean by that, because the opposing effects of performance standards and the economics of mass production tend to push most commercial products toward the same region of the solution space.



Mike Halloran
Pembroke Pines, FL, USA

 

[CapriRacer]

bljnv,

No, we are using the word "mounting" and "assembly" to mean the same thing - installing the tire on the wheel, not installing the wheel onto the hub. Let me reiterate, the reason for those letters is to describe the contours and they should allow for ease of mounting the tire onto the wheel.

As a side note: Those letters have nothing-what-so-ever to do with how the wheel mounts onto the vehicle and everything-to-do with how the tire mounts onto the wheel.

And, again, strength is independent of the letters. The exception to that would be if a wheel manufacturer were to produce the same wheel in both configurations and I don't think anyone does that.

 

[Xwheelguy]

Been on vacation for a while and just getting back - hence the late response.

In my experience with rim design and testing, the biggest factor in fatigue life was usually relative to the wall thickness of the rim and the processing rather than the shape of the profile. Also, not all rims are required to pass the same fatigue tests - some automakers are still using vertical impact tests which are much more severe to the rim than the more modern impact test requirements used by other automakers. With that being said, it's a little difficult (for me) to predict which well design is better - never designed or tested a double well rim. Probably a different application than a light truck or passenger car (I was usually dealing with J(ISO) profiles).

When we needed more clearance to ease the mounting of a tire for a wide rim, we just made the drop well area wider - if memory serves correctly, there was just a minimum distance between radii in the drop well, not a maximum limitation.

Tim Flater
NX Designer
NX 9.0.3.4 Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB

 

[Tmoose]

When alloy wheels became OEM in the 80s some were famous for bending easily when encountering potholes etc. This was with 14 and 15 inch diameter and cushiony 70 series tires too.

http://s1.cdn.autoevolution.com/images/gallery/PEUGEOT505-2819_4.jpg

http://auto-database.com/image/volvo-740-wallpaper-2376.jpg

The damage I saw (and occasionally repaired) was almost invariably on the "back" edge which was cantilevered WAY out there and least supported.


Some makes shifted the interface of the wheel disk and rim inboard, effectively reducing the cantilever.

http://www.davebarton.com/84_242Turbo_06-13-03-001.JPG

I interpreted this as a method of "strengthening" the wheel, as those seemed much less prone to damage, although it is possible that other changes were made as well.

Dirt bike alloy rims include some form of ribbing to provide resistance to denting.
Initially, with mud collecting flanges right at the edge of the rim.

https://c2.staticflickr.com/2/1346/5105483295_22660101c7.jpg

Later with deeper wells.

http://throttleyard.com/wp-content/...MA_MX_Motorcycle_For_Sale_Rear_Hub_resize.jpg

http://www.factory-mx.com/v/vspfiles/assets/images/talonexcelredblk.jpg

Perhaps also with Maybe fancier alloys and heat treating, since I have several from different suppliers long ago that have spontaneously cracked right at the rim's welded seam.

I imagine a second well //might// provide better pot hole dent resistance