Dunlop Claims MT rim diameter different than CT, who can verify?

[OutKast]

As a serious CT prospect, I encountered this on Dunlop's website. I was actually looking for real tech info for a friends question why he could not run "front" tire on rear and vice versa.

 

So, do any of your guys have the equipment and a spare rim to actually measure a 15" motorcycle rim and a 15" car rim and report? I think equipment to measure thousandth would be in order.

 

Here is the quote from Dunlop's site:

 

For 15-inch motorcycle replacement tires, never mount on a 15-inch diameter passenger car tire rim. Mount only on a 15 M/C motorcycle rim. These passenger car and motorcycle rims actually differ in diameter.

 

 

 

This statement is on this page:

http://www.dunlopmotorcycle.com/infocenter_tiretips.asp?id=27#tip

[pegscraper]

I have neither a spare rim nor calipers that will measure that big. I really question Dunlop's statement though. There are too many of us around doing this. I have heard of a number of issues and potential issues and rumors of issues, but I have never heard of that one anywhere. It sounds like a CYA statement to me. And of course, a motorcycle tire manufacturer doesn't want to lose sales.

[footsie]

The difference is the bead seat, the raised area the bead of the tire has to jump over to seat. Its larger on the motorcycle rim. My nexum tire popped out at 70 psi after it was lubed with murphy lube.

 

Gregg

[OutKast]

I agree with you Peg, really hoping to disprove it. But it is also my understanding that there is some trouble with bead seating.

 

I am in search of Truth!!!!!

 

If Dunlop's statement is true, we could compare ANY 15" motorcycle wheel with any 15" car wheel. If someone had access to a dial caliper and a repeatable way to center the wheel, it would be easy. I have a spare rear wheel from a 1200 gl Goldwing, will check tomorrow to see if it is 15". If it is, there is a machinist in my local CMA chapter.

 

If anybody else has a way to research this, please do and see what you find out.

[BigBoyinMS]

From my experience a couple of weeks ago I don't think the diameter is different but there is a bead just past the lip that the tire has to get over. And it is a beach to get over it!

But I have a couple of hundred on mine now and no problems.

[thebighop]

I have stated this in the past..

 

Having worked with engineers and company reps for most of my career at General Motors and Delphi...I believe I can say quite confidently, that no engineer, or company rep, is going to say a damned thing, about using their products, on anything, but that which they expressly developed for , out of fear of liability.

 

I run a rear on the front of my Venture...anyone that runs a OEM sized tire on the front of their Venture does likewise....

Now, there are some manufactuares that list them as fronts, but the majority...Dunlop included as I recall, list the 150/80/16 as a rear

 

As for comparing the rims of a Venture to an automobile...you would have to look at nearly every manufacturer of auto rims, as they all have some design differences...

 

I have ran CT's on my bikes since the late 60's, when I picked up the practice from some old timers that could never find a decent MT for their Harleys and Indians....

I have never had any problems using CT's, and that goes all the way back to the days when tires weren't anywhere near as good as todays tires...

The biggest difference was we didn't have all the pavement we have today and we rode on a lot of dirt roads back then...

 

I think Peg settled the arguement a few posts back, when he said... "I really question Dunlop's statement though. There are too many of us around doing this."

[OutKast]

Mr. Big,

 

FACT -the front stock size E2 I removed from my bike stamped "FRONT WHEEL FITMENT ONLY"

 

FACT - the front stock size E3 I installed on my bike stamped "FRONT WHEEL USE ONLY"

 

FACT - The stamping on both these tires is raised letters cast in during production, not "stamped" in after production.

 

FACT - Dunlop states MT rims are a different diameter from CT.

 

FACT - regardless of manufacturer, all CT rim diameters would have to be within a certain tolerance, because we can mount any brand tire on any brand rim.

 

FACT - numerous darksiders express difficulty with getting the CT over the bead.

 

From these facts, my THEORY is (and if you do not know the differance between fact and theory, close this thread NOW!) that only the bead diameter is larger.

 

Now, the process of proving or disproving theorys consists of collecting more facts that prove or disprove beyond a shadow of a doubt.

 

Bringing in additional unrelated conspiracy theories, such as "all stock tired ventures run a rear tire on the front" only diverts our attention away from the TRUE FACTS I am in search of.

 

So, my original question stands, does anyone that cares have access to equipment to verify or dispute Dunlop's claim?

 

FACT - two darksiders have stepped foward and stated they feel bead diameter is larger.

[thebighop]

Fact...the E3 on the front of my Venture has raised letters that say for "rear wheel use only"...and it is a 130/90/16...which is smaller than the OEM 150/80/16 that came with the bike and which is the factory recommended replacement size as per my owners manual...

 

Fact...the OEM tire I took off the front this past spring is a 150/80/16 E3 and it also has raised lettering saying for "rear wheel use only"

 

Fact....I stated that most are listed as rears...including Dunlops...I did not all all are listed as such. Obviously, Dunlop lists them as both...

 

I deal with OEM car rims on a daily basis...as a service rep for several rim manufactures, and I can safely say that if you are checking in the thousandths for rim dimensions , you will find variances....they will fall with-in a standard dimension that any tire can fit, providing it is the proper diameter and width.

 

But in re-reading your original post...I note that the warning is to not use an MT on a car rim....

I am guessing here, but I believe what they are warning about is....a car rim is wider than a motorcycle rim, so a MT may not span the width of a car rim.

 

A CT mounted on a narrower motorcycle rim, would easily fit, once past the bead.

 

Fact...a stock rim on the rear of a Venture is 4 inches wide, and the narrowest 15 inch car rims I know of are 6 inches wide.

Let me clarify that...I said the "narrowest 15 inch car rims I know of "...that means there are probably some that are narrower...I just don't know of them.

 

I will look into the dimensions for the car rims..as I have access to the manufacturers specs...and I will see if I can pull up some motorcycle rim specs as well.

 

Sorry dude...I didn't mean to get your hackles up like that...

Edited October 5, 2008 by thebighop

[Freebird]

My feathers are not ruffled at all but your FACTS are just wrong. The RSV comes stock with either the Bridgestone or Dunlop tires. What is the Dulop...404 or 440, don't remember for sure but I do know for sure that they NEVER came with the E3 from the factory. So, you saying that the OEM tire was a rear E3 is just not correct. SOMEBODY had to have changed that tire at some point. I've never seen a Venture come from the factory with a rear tire mounted on the front and I've not personally seen a front tire that even looks like a rear tire. Typically they have a bit different tread and slightly different profile.

 

If your tires had "rear only" stamped on them, then somebody put the wrong tires on it.

[thebighop]

For the record...

What I should have written is....

 

the OEM sized tire I took off the front this past spring is a 150/80/16 E3 and it also has raised lettering saying for "rear wheel use only"....

 

But I am not looking to argue about it.