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 wheel rims

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iveco4x4
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PostSubject: wheel rims   Mon Apr 14, 2014 8:28 am

what do the letters mean in wheel rim sizes ?

I have some 6.5h rims for the iveco - normally expect to see J at the end of the width number

ta muchly

rich

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PostSubject: Re: wheel rims   Mon Apr 14, 2014 4:56 pm

[quote="iveco4x4"]what do the letters mean in wheel rim sizes ?

I have some 6.5h rims for the iveco - normally expect to see J at the end of the width number

Good question, I found this on t tinterweb which I think explains what you want to  know, as I read it it looks like H rim has an extra bump in the rim to hold the bead of your tyre against the outside edge of the rim. There's a link at the end of the info to the page which has drawings and charts that explain all.
Hope this helps. Rob


J, JJ, K, JK, B, P and D : Tyre bead profiles / rim contour designations.

[beadprofile]
No, my keyboard letters weren't stuck down when I typed this. The letter that typically sits between the rim width and diameter figures stamped on the wheel, and indicates the physical shape of the wheel where the tyre bead meets it. In the cross-section on the left you can see the area highlighted in red.
Like so many topics, the answer as to which letter represents which profile is a long and complicated one. Common wisdom has it that the letter represents the shape. ie. "J" means the bead profile is the shape of the letter "J". Not so, although "J" is the most common profile identifier. 4x4 vehicles often have "JJ" wheels. Jaguar vehicles (especially older ones) have "K" profile wheels. Some of the very old VW Beetles had "P" and "B" profile wheels.
Anyway the reason it is an "awkward topic to find definitive data on" is very apparent if you've ever looked at Standards Manual of the European Tyre and Rim Technical Organisation. It is extremely hard to follow! There are pages and pages (64 in total) on wheel contours and bead profiles alone, including dimensions for every type of wheel you can think of (and many you can't) with at least a dozen tabled dimensions for each. Casually looking through the manual is enough to send you to sleep. Looking at it with some concentration is enough to make your brain run out of your ears. To try to boil it all down for you, it seems that they divide up the rim into different sections and have various codes to describe the geometry of each area. For example, the "J" code makes up the "Rim Contour" and specifies rim contour dimensions in a single category of rims called "Code 10 to 26 on 5deg. Drop-Centre Rims". To give you some idea of just how complex / anal this process is, I've recreated one such diagram with Photoshop here to try to put you off the scent.

A reproduction of an ETRTO diagram describing rim contour design
From the tables present in this manual, the difference in dimensions between "J" and "B" rims is mainly due to the shape of the rim flange. This is the part in the diagram defined by the R radius and B and Pmin parameters. Hence my somewhat simpler description : tyre bead profiles.
Note that in my example, the difference between "J" and "B" rims is small but not negligible. This area of rim-to-tyre interface is very critical. Very small changes in a tyre's bead profile make large differences in mounting pressures and rim slip.
"A" and "D" contour designations come under the category of "Cycles, Motorcycles, and Scooters" but also show up in the "Industrial Vehicles and Lift Trucks" category. Naturally, the contours have completely different geometry for the same designation in two different categories.
The "S", "T", "V" and "W" contour designation codes fall into the "Commercial Vehicles, Flat Base Rims" category. The "E", "F", "G" and "H" codes fall into the "Commercial Vehicles, Semi-Drop Centre Rims" category. Are you beginning to see just how complex this all is?

I think the best thing for you, dear reader, is a general rule-of-thumb, and it is this : if your wheels are stamped 5J15 and you buy 5K15 tyres, rest assured they absolutely won't fit.

H, H2, FH, CH, EH and EH2 : Hump profiles.

More alphabet soup. So you might have just about understood the bit about bead profiles, but there's another design feature of wheel rims. The 'hump' is actually a bump put on the bead seat (for the bead) to prevent the tyre from sliding off the rim while the vehicle is moving. As with rim contours, there are several different designations of hump design and configuration, depending on the number and shape of the humps. For the inquisitive reader, here's a table of the hump designations, and a diagram similar to the one above which displays in nauseating detail just what a hump really is. The eagle-eyed amongst you (or those paying attention) will notice that this diagram is an enlarged view of the area around Pmin in the other ETRTO diagram above, because that's typically where the hump is.

Designation Bead Seat Contour Marking
Outside Inside
Hump Hump Normal H
Double Hump Hump Hump H2
Flat Hump Flat Hump Normal FH
Double Flat Hump Flat Hump Flat Hump FH2
Combination Hump Flat Hump Hump CH
Extended Hump Extended Hump Extended Hump EH2
Extended Hump 2+ Extended Hump 2+ Extended Hump 2+ EH2 +
etrto hump contours


Read more: http://www.carbibles.com/tyre_bible_pg4.html#humps#ixzz2ypxMpqcM

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PostSubject: Re: wheel rims   Mon Apr 14, 2014 7:33 pm

I got lost after " I've have some"

I've only ever heard of the "J" profile didn't realise there were so many different types

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iveco4x4
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PostSubject: Re: wheel rims   Mon Apr 14, 2014 11:53 pm

To tell you the truth, i'm even more confused now

its bad enough these rims are tubeless split rims but i can get my head around that, now I can't get a tyre to test fit (no toyo open countries in the country)

and I still don't really understand the previous post, comprehensive though it is , i'll have to go look for the extra bump

Thanks

Rich

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PostSubject: Re: wheel rims   Tue Apr 15, 2014 5:24 pm

iveco4x4 wrote:
To tell you the truth, i'm even more confused now

its bad enough these rims are tubeless split rims but i can get my head around that, now I can't get a tyre to test fit (no toyo open countries in the country)

and I still don't really understand the previous post, comprehensive though it is , i'll have to go look for the extra bump

Thanks

Rich

Hi Rich
If you haven't then you must visit the page to read the article and look at the "H" chart and drawings together, J rim = standard tubeless rim your H rim according to the chart should have a hump at the outside of the rim that the J does not, however your rim is a split rim so I am assuming this hump will be just inboard of where the ring and retainer are situated. Your H code wheel is for commercial vehicles and is a semi-drop centre rim, your tyre has to be the same code ie. a H tyre to fit a H rim etc if not the the tyre bead will not fit the rim correctly and there is risk of failure.

Quote from the article:
"The "S", "T", "V" and "W" contour designation codes fall into the "Commercial Vehicles, Flat Base Rims" category. The "E", "F", "G" and "H" codes fall into the "Commercial Vehicles, Semi-Drop Centre Rims" category. Are you beginning to see just how complex this all is?

I think the best thing for you, dear reader, is a general rule-of-thumb, and it is this : if your wheels are stamped 5J15 and you buy 5K15 tyres, rest assured they absolutely won't fit.
End of quote.

regards. Rob

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PostSubject: Re: wheel rims   Tue Apr 15, 2014 9:39 pm

So for the sake of discussion can i fit a 255/85/16 bfg KM2 to these rims ?

Cannot seem to find a reference to rim type in the spec on bfg's website

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PostSubject: Re: wheel rims   Wed Apr 16, 2014 5:41 pm

iveco4x4 wrote:
So for the sake of discussion can i fit a 255/85/16 bfg KM2 to these rims ?

Cannot seem to find a reference to rim type in the spec on bfg's website

Hi Rich
I only know what I've read on the site I'm referring to, it's as much a learning curve for me as it is for you so I cannot recommend tyre sizes but bfg must be able to answer that one in their tech department.

According to the article you should fit same code tyre to same code rim but the only H rating I can find on a tyre refers to the speed rating and not a rim profile so it seems this highly complex area gets more confusing, on further searching I have found yet another H rating which refers to ply rating H being 16 ply?

Do the rims you have give the manufacturer name?
regards. Rob

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PostSubject: Re: wheel rims   Tue Apr 22, 2014 6:07 pm

iveco4x4 wrote:
what do the letters mean in wheel rim sizes ?

I have some 6.5h rims for the iveco - normally expect to see J at the end of the width number

ta muchly

rich

Hi Rich
I've come accross some American websites referring to H in their rim sizes and was wondering if this might be the answer, ie. your rim 6ins with 5 stud Holes = 6-5H?

Links to these sites:

http://www.trailertirewarehouse.com/16X6-8x65-Chrome-Modular-Steel-Trailer-Wheel-TTW-MFI166CM8.htm

http://www.americanatire.com/products/aluminum_wheels.html

http://www.apexway.com.tw/Pd/Trailer%20Wheel%20Rim/trailerwheelrim04.php

What do you think?
Rob

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