215/60 Pirelli CN36 on 7R without tube? Spacer?

[swisscheese]

thanks for sharing.

So, are they flat ledge on outside or taper seat?

6r:


7r:

[2.5MFI]

hi Mark, thnx.
What spacer was used? No grinded bolts or rolled fenders? Any photos of your set-up?
Tom

No rolled fenders, 5mm spacers on the rear and 930 brakes stuffed in there too.

[swisscheese]

No rolled fenders, 5mm spacers on the rear and 930 brakes stuffed in there too.

nice set-up! wow, 5mm spacers and no issues. Torsion bars are stiffer, I assume?

[2.5MFI]

29mm for the rear and I forgot what I put up front. I also have Longballa's through the body bars up front.

[blue72s]

swisscheese,

Thanks for the pics.

Hard to tell what type they are. To be safe, I'd use tubes (Michelin brand only) and 70-series tyres.
Or buy 73RS wheels.

[swisscheese]

swisscheese,

Thanks for the pics.

Hard to tell what type they are. To be safe, I'd use tubes (Michelin brand only) and 70-series tyres.
Or buy 73RS wheels.

They are early Fuchs 6x15 and 7R 15 ("deep dish"). And I don't think the later 7x15 (ET23) will fit with 215/60's in standard '73 fenders.

[Jim Breazeale]

Ask anybody that has ever tried to remove a tire from a "deep6" or real "7R", especially a Michelin XWX. It is virtually impossible to remove it from the front side. Do the same thing with a "flat6" ( introduced in mid year 1971) and it comes right off. The "flat6" has the humps and the "deep6" doesn't. I rest my case. Thank you to Swisscheese for the photos in post #31.

Ciao

Jim

[911MRP]

I think there's the additional issue of the valve holes with running deep 6 / 7R without tubes. These wheels won't seat a tubeless valve securely without modification. They can be modified but finding someone you can trust to do it isn't easy.

Interesting point. Any chance of different angle of that area on the two examples posted. Since the hole was designed for a tube stem it looks like a tubeless valve might be hard to fit and seat securely in an area not designed for tubeless stem. Further to the insurance and liability point. Who is responsible in event of a problem due to failure around valve if wheel was never intended for tubeless use: owner, driver, the workshops who did work, that shop's liability insurer, or car owners motor insurance company?
Important to be clear on that upfront before going ahead with potentially safety critical modification that might turn out to be the root case of a rapid deflation and in worst case loss of vehicle control. I don't know about other countries but liability in event of an accident in UK could be a significant legal and financial concern if someone has gone ahead to make a modification or fit a combination not approved by wheel, tyre or tyre valve company. Motor insurance can be invalidated by undeclared unapproved modifications. As stated several times its important to take qualified expert advice on current position on such things rather than giving the tubeless stem or seating modification a go and hoping it is safe. Rapid loss of pressure in a car tyre can be very serious.

Has anyone explicitly asked their motor insurer upfront as part of policy car declarations if the insurer/underwriter are explicitly ok with these practices and risks and on return got written confirmation that it is ok to do things like: fit tubeless tyres on rims without humps; fit tubes to low profile 60 percent aspect ratio tyres; or locally modify old tubless rims valve stem holes to accept tube type valves ?

Somehow I doubt that this is the way this typically gets done. In which case doesn't a keep quiet or even deliberatly not declare to mislead them approach speak volumes? Particularly when this matter has been discussed before so the potential risk or concern is known? This community is into details so not being aware of a potential concern about tyre rim and valve configurations less likely than someone who has no interest in their old vehicle.

I am not an expert so don't feel qualified to make potentially safety critical tyre and wheel and valve configuration recommendations to others. From what I've seen major tyre companies, who have vast resources so know a lot more about the subject than me, have in past and still do afaik have technical data and formal technical positions on the do's and don'ts of such configurations. I personally don't ignore that. I don't do any of these things myself since it seems to be just for cosmetics.

[swisscheese]

Interesting point. Any chance of different angle of that area on the two examples posted. Since the hole was designed for a tube stem it looks like a tubeless valve might be hard to fit and seat securely in an area not designed for tubeless stem. Further to the insurance and liability point. Who is responsible in event of a problem due to failure around valve if wheel was never intended for tubeless use: owner, driver, the workshops who did work, that shop's liability insurer, or car owners motor insurance company?
Important to be clear on that upfront before going ahead with potentially safety critical modification that might turn out to be the root case of a rapid deflation and in worst case loss of vehicle control. I don't know about other countries but liability in event of an accident in UK could be a significant legal and financial concern if someone has gone ahead to make a modification or fit a combination not approved by wheel, tyre or tyre valve company. Motor insurance can be invalidated by undeclared unapproved modifications. As stated several times its important to take qualified expert advice on current position on such things rather than giving the tubeless stem or seating modification a go and hoping it is safe. Rapid loss of pressure in a car tyre can be very serious.

Has anyone explicitly asked their motor insurer upfront as part of policy car declarations if the insurer/underwriter are explicitly ok with these practices and risks and on return got written confirmation that it is ok to do things like: fit tubeless tyres on rims without humps; fit tubes to low profile 60 percent aspect ratio tyres; or locally modify old tubless rims valve stem holes to accept tube type valves ?

Somehow I doubt that this is the way this typically gets done. In which case doesn't a keep quiet or even deliberatly not declare to mislead them approach speak volumes? Particularly when this matter has been discussed before so the potential risk or concern is known? This community is into details so not being aware of a potential concern about tyre rim and valve configurations less likely than someone who has no interest in their old vehicle.

I am not an expert so don't feel qualified to make potentially safety critical tyre and wheel and valve configuration recommendations to others. From what I've seen major tyre companies, who have vast resources so know a lot more about the subject than me, have in past and still do afaik have technical data and formal technical positions on the do's and don'ts of such configurations. I personally don't ignore that. I don't do any of these things myself since it seems to be just for cosmetics.

So, just out of interest: What is the point you're trying to make here?

[911MRP]

You asked the question

I know there are many threads about tires and 7R rims, but couldn't find an answer on this one: Am planning to fit a 215/60-R15 Pirelli CN36 on deep 7R; Is it possible to mount these without inner tube? What spacer is required on a 73S (non-rolled) rear fender? Front would have a deep 6 with 185/70-R15 CN36. I understood the Avon is a much wider tire than the CN36 in the same width? (couldn't find anything on CN36 / 7R / spacer / tube combo). thanks in advance!

In 1972 Pirelli on Germany published this viewpoint:


In 1974 Michelin (who are credited as being the company who commercialised tubeless radial) published this technical data about Porsche wheels:

The footnote annotations are important.

Technical data from tyre manufacturers can change so this is for historical reference only and may not represent the current position.

Since at one time Pirelli ( and Michelin) did think it important enough to publish a view on the do's and don'ts. So it seems logical to ask Pirelli about the do's and don'ts of using their current tubess CN36 product on older Porsche wheels -- those designed without humps and without tube type valve stem holes.

Given the resources of companies like Pirelli and the fact they are a partner of Porsche today their answer would factually inform any rational decision on the question.

Although the original question does not ask about use of tubes this Pirelli wrote this about using tubes in tubeless:



Pirelli's contact details are shown on the above so it ought to be a simple matter for someone facing this concern to write and check all points directly with the tyre manufacturer if they are proposing Pirelli product such as CN36.

To follow (or deliberatly ignore) any current technical position of a product manufacturer is of course an owners prerogative. To ignor their position on a safety critical application might not be wise, however.

Depending on what the manufacturer says today it might raise another question. Particularly if current tubeless tyres on rims designed for tubes are not supported by Pirelli (or other alternatives like Michelin Avon etc). A dilemma for those invested in old Porsche wheels designed for tube tyres.

Would an provider of motor insurance cover invalidate the policy if they knew that the configuration of the car being proposed did not conform to tyre company technical position on acceptable configuration: tubeless without humps and / or the tube type valve hole (or accept of seating had been modified locally as a work around?) Driving without valid insurance or without disclosing such non compliant things thereby invalidating insurance policy through lack of disclosure in light of information might be a significant legal and potential liability here in the UK. I don't know about other countries.

Great the nettle. Why not ask Pirelli (Michelin Avon etc ) as it seems likely being serious well run companies they'll have a considered and technically informed view on how their product should be used.

Also why not openly discuss the available options and configurations with the insurer beforehand. Do so based on whatever the current tyre company factual technical position is found to be? Better to find out the position before than get a surprise in event of a claim?

Has anyone already got a written current factual point of view from Pirelli ( or Avon or Michelin) also a motor insurer.opinion about providing cover explicitly about these configuration points already?

To be clear I'm no expert. I don't know what the tyre companies or insurers will say today (although I can see the original view from 70s above). For that reason I don't recommend one way or another. I simply want folks to seek the best information to be technically compliant with their tyre manufacturer's position on tyre, rim, tube and valve configurations they support (or prohibit) . For cars to be safe, legal and not have a potentially big unexpected liability in some extreme situation.

I assumed the original question was not simplistically will it physically fit in the space with no consideration of the more important fundamental questions. It's either okay; or it its not. I don't make the rules.

Steve