# fitting spare wheel on to a tow bar



## Philippft (Feb 16, 2008)

My spare wheel is under our bed and restricts me from storing additional items I would like to store there. 

Whilst I have a tow bar fitted, I do not yet have a trailer and it struck me it must be possible to fit the spare wheel directly onto the Tow bar ball with a simple attachment ? 

Well, I've been searching on the internet and to date I am unable to find such a device. Has anyone come across such a device and if so can you provide me with details please. 

Thanks in advance, 

Philip


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## teemyob (Nov 22, 2005)

*Made*

If such a thing does not exist, I am sure someone could make one.

Or use a Thule carrier/carrier box?

TM


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## teemyob (Nov 22, 2005)

*crude*

Here is one (not the neatest looking thing)

Click


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## peedee (May 10, 2005)

I have been thinking along similar lines simply because I do not yet have a spare wheel. I think it all depends on its weight and whether you would be overloading the rear axle. I have one of >these< and thought I might be able to carry one on this on trips where breakdown services might not be so good.

I would be interested to know what a spare wheel weighs, any idea ?

peedee


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## teemyob (Nov 22, 2005)

*meant*



peedee said:


> I have been thinking along similar lines simply because I do not yet have a spare wheel. I think it all depends on its weight and whether you would be overloading the rear axle. I have one of >these< and thought I might be able to carry one on this on trips where breakdown services might not be so good.
> 
> I would be interested to know what a spare wheel weighs, any idea ?
> 
> peedee


Thats what I meant. Not sure how bog the box is to put it in if you bought the box!?

And then thee is the EZTow!?


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## peedee (May 10, 2005)

Interesting idea on the jeep, worth investigating further. Thanks Teemyob. I have checked if I could fix one to the back like a bike rack but the cost of reinforcing to take the weight etc would be prohibitive and it is cheaper to take the risk and pay the breakdown company for any service required.

peedee


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## rogerblack (May 1, 2005)

peedee said:


> Interesting idea on the jeep, worth investigating further. Thanks Teemyob. I have checked if I could fix one to the back like a bike rack but the cost of reinforcing to take the weight etc would be prohibitive and it is cheaper to take the risk and pay the breakdown company for any service required.
> 
> peedee


Have you checked the basis of your breakdown cover? I thought that they won't deal with e.g. punctures unless you were carrying a spare wheel . . .


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## rayc (Jun 3, 2008)

I have had good service from CMF Trailers at Ross on Wye. They manufacture a tow bar fitted wheel carrier, I had a modified version to fix it inside my garage.
http://www.cmf-engineering.com/t-home/


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## rayc (Jun 3, 2008)

peedee said:


> I would be interested to know what a spare wheel weighs, any idea ?
> 
> peedee


I can lift my 16" spare into my garage so it can't be that heavy as I am no Geoff Capes. My guess is 30kg max.


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## peedee (May 10, 2005)

rogerblack said:


> Have you checked the basis of your breakdown cover? I thought that they won't deal with e.g. punctures unless you were carrying a spare wheel . . .


Yes, they will but will charge for the call out, that seems to be most breakdown services stance. I will have to call them out anyway even if I carried a spare.

peedee


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## peedee (May 10, 2005)

Thanks for all the info Rayc, I guess I will have to get a spare wheel first. Think my towball carrier is rated at 65Kgms and I fairly sure the rear axle loading will take the weight of a spare wheel. Looks like I have a couple of options to explore further having eliminated the possibility of fixing one to the rear panel

peedee


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## Philippft (Feb 16, 2008)

Thanks to one and all, very helpful. 

I like the idea of the Thule carrier as it can be simply adapted to carry multiple items. I'm getting conflicting weight limit capacity information though some web sites state 60 Kg. However the Thule website states 45 Kg. with the carrier itself weighing 15Kg. 

I believe the maximum loading weight for my tow bar (nose weight) is 90 Kg. and as I'm already carrying the spare wheel under the bed i will only be increasing the load on my axle by 15Kg. 


Anyway, I'm on the right track now, thanks again.


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## peedee (May 10, 2005)

Philippft said:


> I like the idea of the Thule carrier as it can be simply adapted to carry multiple items. I'm getting conflicting weight limit capacity information though some web sites state 60 Kg. However the Thule website states 45 Kg. with the carrier itself weighing 15Kg.


I agree and that was the reason I bought it. I am sure mine was rated at 65Kgm. At the time two models were available and I purchased the one with the greater carry capacity. So far I have carried a bike and a drive away awning on it without problem.

peedee


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## Philippft (Feb 16, 2008)

[/quote] 
I agree and that was the reason I bought it. I am sure mine was rated at 65Kgm. At the time two models were available and I purchased the one with the greater carry capacity. So far I have carried a bike and a drive away awning on it without problem.

peedee[/quote] 
I've just measured the diameter of my spare wheel which is 670 mm (I would need to lay it flat and according to the specification sheet the width of the frame is only 600mm. I could overhang the wheel slightly on the Motorhome side of the frame as I have 160 mm gap between the towing ball and the back of the motorhome. However, when I go back to the specification of the frame it shows that no mass should extend 400 mm from the tow bar itself. So, I guess I'm stuffed with that plan but I have another.


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## peedee (May 10, 2005)

I am considering standing the wheel vertically against the back of the Thule rack, Cannot go any further with the idea without a wheel to check what might be available to fix it like this.

peedee


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## Philippft (Feb 16, 2008)

peedee said:


> I am considering standing the wheel vertically against the back of the Thule rack, Cannot go any further with the idea without a wheel to check what might be available to fix it like this.
> 
> peedee


I misread the specifications, so I can carry my spare wheel on it after all. I've just purchased one on line and will let you know how best to fit the wheel on the carrier. I'm certain it will fit lying flat which would be great.


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## bubble63 (Sep 30, 2009)

how about this

ebay rack

or this

bak rak

neill


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## Philippft (Feb 16, 2008)

Thanks to Teemyob I have now found a solution to carrying my spare wheel. 
The Thule Easy Base works has solved my problem. I now have the option of carrying the spare wheel on the back which frees up quite a lot of space under the bed, plus i can alternate how I carry my loads and have a combination of different objects on the carrier. 

As you can see from the photo it fits quite well, all i have to do now is find a way of securing it to the carrier which should be straight forward. 
Incidentally the wheel weighs 26.2 Kg.


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## rosalan (Aug 24, 2009)

peedee said:


> Think my towball carrier is rated at 65Kgms and I fairly sure the rear axle loading will take the weight of a spare wheel.
> peedee


If the tyre weighs 40kg's and the distance from the axle is more than six feet (+/-) the actual load on the axle (payload) may be 80kg, the actual statistics were on my 'icampsites' usb I think but it was stolen so cannot check up.
The point being that many vans have payloads not a lot greater than 200 kg's and a weight like 80kgs may not be practical
Alan


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## Philippft (Feb 16, 2008)

If the tyre weighs 40kg's and the distance from the axle is more than six feet (+/-) the actual load on the axle (payload) may be 80kg, the actual statistics were on my 'icampsites' usb I think but it was stolen so cannot check up.
The point being that many vans have payloads not a lot greater than 200 kg's and a weight like 80kgs may not be practical
Alan[/quote]

Alan, the wheel weighs 26.2 Kilo's !

Also, I fail to see how the mass of a load can increase just by moving it along a straight line.The two constants are Mass plus gravity and neither of these change as the mass is moved along. However, I do accept the mass has an effect on the amount of leverage applied as it is moved further away from the fulcrum ?
Not quite sure what forces are at work on the Tow bar arrangement and I'm not worried as the mass on her carrier is within manufacturers weight limits and the combined mass of spare wheel and carrier within the weight limits set by the company who installed the Tow bar.


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## peedee (May 10, 2005)

When I last weighed my 6.5 ton van in near travel trim I had a ton to spare most of which is on the rear axle  I also do not have a large overhang my model being some 4 ft shorter than the standard model

If I ever get round to getting a spare wheel I will of course take it to the weigh bridge with it on the towball.

peedee


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## DTPCHEMICALS (Jul 24, 2006)

Philippft said:


> If the tyre weighs 40kg's and the distance from the axle is more than six feet (+/-) the actual load on the axle (payload) may be 80kg, the actual statistics were on my 'icampsites' usb I think but it was stolen so cannot check up.
> The point being that many vans have payloads not a lot greater than 200 kg's and a weight like 80kgs may not be practical
> Alan


Alan, the wheel weighs 26.2 Kilo's !

Also, I fail to see how the mass of a load can increase just by moving it along a straight line.The two constants are Mass plus gravity and neither of these change as the mass is moved along. However, I do accept the mass has an effect on the amount of leverage applied as it is moved further away from the fulcrum ?
Not quite sure what forces are at work on the Tow bar arrangement and I'm not worried as the mass on her carrier is within manufacturers weight limits and the combined mass of spare wheel and carrier within the weight limits set by the company who installed the Tow bar.[/quote]
The mass of the load does not increase but the effect it has when it is placed further away from the pivot point does. Your steering will be lighter and the load on the rear axle will be increased
Dave p


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## airstream (Jan 7, 2009)

*explained here*

Hi,
Good explanation here on overhang weight

http://www.caravanguard.co.uk/news/how-to-calculate-your-motorhome’s-safe-weight-limits-4104/

However some one stated on MHF that a rule of thumb 10% per foot of overhang from rear wheel ctr to ctr of load was about correct ie 100kg load at 6ft adds approx 160kg to your rear axle

I just nipped down to the weighbridge = shock horror = uprated rear axle loading, thanks to SVTEC

All legal now

Ray


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## Philippft (Feb 16, 2008)

[/quote]
The mass of the load does not increase but the effect it has when it is placed further away from the pivot point does. Your steering will be lighter and the load on the rear axle will be increased
Dave p[/quote]

That makes sense to me Dave. However, as the spare wheel was already under the bed and the only additional mass added is 15 KG (the carrier). I found no noticeable change when driving with this set up.

All the best!


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## Gretchibald (Jul 22, 2011)

I do realise that many on here don't have any engineering skills or perhaps facilities but what you are looking for would be 'wee buns' as they say here for anyone who has even basic eng skills to design and make. Suggest you ask around , save yourself some money and get one made that looks right for your MH-- also have it galvanized or if money is not a big issue ,made from stainless steel .


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## Philippft (Feb 16, 2008)

Gretchibald said:


> I do realise that many on here don't have any engineering skills or perhaps facilities but what you are looking for would be 'wee buns' as they say here for anyone who has even basic eng skills to design and make. Suggest you ask around , save yourself some money and get one made that looks right for your MH-- also have it galvanized or if money is not a big issue ,made from stainless steel .


OK I'll rise to this one! 
Can you explain what a wee buns is ? where it fits and how it functions!
I have never come across this term before.


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## VanFlair (Nov 21, 2009)

Hi

Back to "turning moments" again.

If you put 25kg 6 feet back from the back axle the moments are 6x25 clockwise so 150.

The clockwise moments are balanced by the counterclockwise moment which basically lift weight from the front axle.

The weight off the front axle has to add up to the same 150 moments although in the opposite rotational direction.

If your wheelbase is 18 feet then divide 150 by 18 and you get 8.33 this is the kg lifted off the front axle and has to add onto the back axle load as you can not loose mass completely.

In this example you would be increasing the back axle load by 25+8.33kg and decreasing the front axle load by 8.33kg.

Martin


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## airstream (Jan 7, 2009)

*simple*

Hi,
Simple or easy or as they say over there so they do "wee buns"

Ray


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## rayrecrok (Nov 21, 2008)

VanFlair said:
 

> Hi
> 
> Back to "turning moments" again.
> 
> ...


Hi.

Or just compress the rear suspension by the amount of lever force ?.

ray.


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## Medallionman (Nov 26, 2005)

VanFlair said:


> Hi
> 
> In this example you would be increasing the back axle load by 25+8.33kg .
> 
> Martin


Less if you inflated the tyre with Helium! :lol: 
Brian


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## VanFlair (Nov 21, 2009)

Hi Brian

If you filled the tyres with Helium it would weigh less on the weighbrodge but the weight on all the vehicle running gear would be the same.

I think.

Martin

While we are getting silly, if a bird is sat in a jumbo jet and then decides to fly around the plane (not fly the plane around) will the plane weigh less ???.


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