Topic: Domestic dispute

[medic09]

Okay, you all get to settle a domestic dispute.

The wife (aka 'wife') is putting air in the tires on her '02 Shadow VLX.  She has fairly new Dunlops on there.  The label on the chain guard has Honda recommendations.  29-36 psi (rear tire) depending on load.  Dunlop has on the tire 41 psi for max load.

I told her I would go with tire manufacturer's recommendations.  She says "but the Honda label says..."

What say you all?   

Wife saw this and beat me!    Help! 

[Sam Green Racing]

Go with the tyre manufacturers recommendation, they made it and know what loads differing pressures are require.

The pressure advised by Honda is for the tyre that was fitted from new.

Sam.

P.S. you win....sorry wife

[medic09]

Well, Sam, now you and I are in the doghouse together! I can't even spell my wife's reaction to your post. 

Interesting, I just went to the Dunlop site (she has D404s on her bike).  Here's what they say as general guidelines:

"For high-speed, fully loaded or dual-riding touring motorcycle applications, inflate front tires to maximum recommended by vehicle manufacturer for Dunlop fitment and rear tires to maximum load inflation pressure on sidewall. Rear touring tires must be inflated to a minimum of 36 psi for light to medium loads and 40 psi for dual riding and other loads."

Sounds like 'front tire go with Honda, rear tire go with Dunlop'! 

On the tire sidewall they only list a max pressure of 41. So for her light riding I'd guess I would go with something around 35-38 psi.  Certainly more than the Honda label's 29.

[clarkjh]

I think I read it on here somewhere but not sure.  Inflate tires cold, ride until warm, then check pressure, if it has increased by about 2 psi then the tire is inflated to the correct pressure for the rider and load.

James

[edbikerii]

Mind your own damned business.  It's her bike, let her make the decision.

(I'll bet she likes this answer  )

[medic09]

Mind your own damned business.  It's her bike, let her make the decision.

(I'll bet she likes this answer  )

Yeah, you got cheered.

Sam and I have to make our own dinner.  So Sam, did you want wet or dry (dog food).   

After seeing the Dunlop site, she went out and put 36 psi in the rear, and the 31 in the front.   I wonder if I could settle our other disputes this easily?   

[merc2dogs]

atually, have to differ a bit.

 the pressure marked on the tire is at max load. it should be marked in the order of max load ###lbs @ 41psi, if you are not at max load, you can drop pressure and smooth out the ride

If you run at the max pressure but only have half the rated load on the tire it will ride rough and telegraph a low level vibration through the suspension, too low for the load and you'll wear out the tire fairly quick.
 
 Too much pressure and the tire will 'bounce' if it hits a bump, too low and it folds over the obstacle too easily and can allow it to hit the rim


 Normally I run a bit higher than recommended, I experimented and found that for my general riding 35 psi great, when I hit the twisties I normally air down a bit to about 30 on both simply because it seems to match my riding better,  but too much can make the bike handle differently

 Tire manufacturer rating is at max load, and is only concerned with load

 vehicle manufacturer rating generally is broken down to loads,  and tries to balance rider comfort with handling, and only applies to tires of the same size that were OEM, and are not always satisfactory for every rider.

 Most riders are happiest when running slightly better than vehicle manufacturer, and less than tire max.

Ken.

[edbikerii]

Well, don't take my relationship advice.  I'm recently divorced -- but couldn't be happier !  I don't know whether I learned something and developed the "hands off attitude" or if that attitude was gradually getting me into trouble all along .

Frankly, I wouldn't take advice from me on tire pressures, either.  I always follow the bike or car manufacturer's recommendations since the Ford Explorer rollover problems came up.  I think I recall that reducing the front tire pressures would correct some suspension geometry problems with the old Explorers, so the Bridgestones (with their different inflation recommendations) got blamed for the rollovers.  Or something like that .  I'd recommend checking with the manufacturer for the specific tire.  On the other hand, they might recommend using the stock tires, in order to avoid liability.

[medic09]

Well, my approach was sort of 1/2 of merc2's.  Since the tire is marked only for max load, I've always used that minus about five as a good point to work at.  I have no evidence for this however.

Merc2 thinks the bike maker recs are not only for original tires.  Sam and I (both in the doghouse  ) always thought it was for the original tires/tyres only.  I have to admit our understanding doesn't make much sense as it doesn't give the maker's engineers much credit.

Hmmm?

Anyone know how Honda actually did these things?  HondaMan?

[Sam Green Racing]

To be honest I went with what made more sense, I run my rears between 8 and 18lbs

Sam.

[333]

This goes for all vehicles- cars, bikes, airplanes... well, maybe not airplanes.  Only the vehicle manufacturer knows the characteristics and weight of the vehicle in question- factors that have everything to do with proper inflation.  Even the tire manufacturers will state this.

So, gotta agree with your wife.  Sorry!

[TwoTired]

If your wife has the size tire that Honda specified, she and Honda are right.

The PSI stamped on the tire is for max load and is related to stresses that the tire can endure safely.

If you put 35 PSI in the tire and then place 1000 lbs on the bike, the tire pressure will likely be above the max rating.  If the manufacturer doesn't put the rating on the tire, someone WILL put 1000 lbs on the bike and inflate the tire to 100 PSI to make it round again.  Then when the tire fails, they'll blame the manufacturer for faulty tires, saying, "well, they didn't tell me I couldn't do that"!

The tire has a weight limit and at that weight limit 41 PSI is the maximum the maunufacturer has designed the tire to operate safely.  Lower weights require lower tire pressure, so the tire settles onto the street and makes a bigger contact patch than it would if over inflated.

Further, if you use max tire pressure and low weight loading, the center of the tread will wear much faster than the outward edges of the tire and you'll be replacing them at much faster intervals due to "square off", also known as "chicken strips".  When these last conditions exist, the bike handling changes, usually for the worse.

Any true biker would know this, of course! 

[medic09]

Well, I wasn't suggesting that she inflate to max (41 psi).  But given that is the max, 29 psi seemed pretty low to me.  The Honda label says 29 for light load to 36 for max load.

Oops, I just noticed that the label specifies *exactly* the tire she has on there (Dunlop D404).  I suppose that means that Honda took all this into account.  Interesting that they specified a tire by brand and model.  More interesting what an idiot I can be sometimes...

[mgmuellner]

I start with the tire manu PSI then go by feel until I like how it's wearing & how it handles.  Then I measure the PSI & keep it there.  My sweet spot is slightly higher than the bike manu but lower than the  tire manu recommendations.

[CrisPDuk]

In the UK the law requires your tyres to be inflated to within 5psi of the vehicle manufacturers recommended pressures.

If your tyres are incorrectly inflated you can be fined/endorsed for using an unroadworthy vehicle and the good bit: Two wrongly inflated tyres means two offences, ie; two fines/endorsements


As TT says, all the tyre manfacturer will tell you is the maximum load/pressure ratings they will warrant their tyre for. It's pretty unrealistic to expect them to know the requirements/characteristics of every vehicle their products are likely to be fitted too

So sorry Medic, you're wrong, your Wife is right   Does that mean I get to eat the dinner she's no longr feeding you if I call round

[mark]

You recommended the MAX LOAD specs???

No wonder you're in trouble!

(pump up the tires some more, dear - that dress makes you look fat)

Happy trails!

[medic09]

I DID NOT suggest max load specs.  I suggested something mid-way, not having read carefully that Honda was recommending for that specific tire.

CrisP, I think she just gives the good stuff to the Labrador, and leaves me to the dog food with our other mutts.    

[CrisPDuk]

That sound's about right Medic