Rims and sizing

[Prof]

Changing rims and tyres and understanding all the implications can be daunting.

I borrowed two wheels off a vehicle to try on another. Nice steel rims...but stamped with 'Trailer use only'.

So wondered about that...
Found this site....
http://www.centrevilletrailer.com/how-t ... ire-facts/

So for 'trailer use only' not good for vehicles as it is designed for straight line use.

Any other pifalls or advice regarding rims? Steel ones.

[Quack]

I feel compelled to reply! None of my vehicles have oe size tyres! Bit most have oe rims!

This for very good reason, as mentioned elsewhere, oe rims are usually stronger, their offset (distance away from the hub) is also normally pretty accurate and promises the least amount of strain on the bearings.

Their centre holes are also normally well matched, which if it is not the case you will need spigot rings or a very steady hand when you fit the wheel to avoid vibrations.

I also find that oe rims are narrower than aftermarket rims in general which helps if you’re deflating tyres, a narrower rim debeads not as easy as a wider rim.

One last trick on the rim side that I’ve employed is to fit a run flat band, not to prevent punctures, but to avoid debeads, so far my result are subjective but possitive, I’ve managed 0.25 bar without a debead!

Now we get to tyres and this is where the fun start! Most vehicles will accept up to 10% bigger circumference without too much fuss! Remember you would put a lot more strain on your drivetrain beyond this point!

You will probably also need a heatgun to modify the plastics in the wheel arches, a lift will help in some instances, but if your vehicle articulates well you will still rub!

To cut down on experimenting cost I will normally use an app or web based wheel and tyre calculator and would normally aim for 10%

Obviously the stronger the vehicle, the more accommodating it would be to tyre choice.




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[BushWacker]

Heres another cross-section diagram
showing the rim dimensions etc

[img][https://ibb.co/mUqrAo/img]

One aspect with regard to wheel-spacer disks
is surely that they change the applied offset
of the rim set-up ...
... and the weight load on a given wheel
is displaced out along the wheel-studs ...
this can lead to stud breakage esp if the
wheel bolts dont tightly clamp the disk etc

[Quack]

Oh, one more tip! Stay away from 19”, you can’t do anything with 19” rims, not in the veld in any case!


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[XJ Junkie]

I also find that oe rims are narrower than aftermarket rims in general which helps if you’re deflating tyres, a narrower rim debeads not as easy as a wider rim.

It’s actually the other way around Quack. Less debeads with wider rims

Or at least that what I’ve experienced

[grips]

When Swambo had the Volla Bus, I left that with OEM rims

On 4x4`s I size rims according to tire sizes. 35`s x12.5 need 10J rims. To be honest I had a debead long ago very long ago.

Thinking of it it is only the 76 Cruiser that is still on its OEM mags, but not for long any more.

[Wooky]

Prof.... You don't say for what type of vehicle and what is the intended application.
This can have a bearing on what rims to fit.

For a vehicle that will see a fair amount of high speed tar then a narrow steelie rim built like a sherman tank and loads of back spacing / offset will possibly not be the best option. Possibly will give you more headaches than they are worth.
For this option I would look for / use a lighter weight steel rim to minimise balancing issues and a rim width close to what is recommended for the tyres you want to fit. The rim width will affect cornering characteristics as this influences how the tyre flexes laterally. Stick to a rim offset that keeps your steering scrub radius about where the OEM rims had it as this will affect steering characteristics as well.

For an offroad toy then things would be very different. Here having rims built like a sherman tank would be a great benefit in avoiding rim damage.
As all speeds will be relatively slow, steering scrub radius is less of an issue but track width can be more important. Using a suitably off set rim will give some small increase in track width.
Fitting a narrow rim in a wide tyre has a few added benefits for an offroad toy. Firstly it increases the lateral instability of the tyre making it flex somewhat easier when you air down. Secondly the narrow rim is further from harm and protected by the sidwall of the tyre, so less rim damage.
The debate about whether or not a narrow rim, in a wide tyre, helps prevent de-beading will be highly subjective but my personal feeling/ experience is that it does help.

Cheers

W

[Prof]

Thanks Wooky

Vehicle is a Daihatsu Rocky.
Currently steel rims, but can't see if they are 7' or 7.5'. Shod with 215R15. Want to go to 245/75R15

Then I got hold of another Rocky, lift here is also about 2' higher than above one. Shod with alloys (only three, got it like that) and 245/75R15

So I will need to buy rims, steel ones.

Last one most likely the prevalent 4x4 vehicle, His. Other will be a Hers.

[Wooky]

Prof,

Have a look here: https://www.wheel-size.com/size/daihatsu/rocky/2002/
Looks like the came with 6jj 15 inch to 7.5jj 16 inch and 8jj 17 inch - not sure what you have.
back spacing is 19mm on the 6JJ and 5mm on the 7.5jj by the looks of it.

You might battle to find the 5X 139.7 PCD in steel rims other than 15 inch.
I was looking to go 16 inch with the same PCD to put on the SJ but have not managed to find any so settled on 15.

Here is a link with recommended tyre width versus rim width - scroll down the page for the table
http://www.tyresizecalculator.com/chart ... size-chart

Hope this helps....

W