M109 Rider Forums banner

1 - 20 of 26 Posts

·
Registered
Joined
·
158 Posts
Discussion Starter · #1 ·
Hi Bros
Need your help. I have fat front - Metz 160/60/18. What shoud be a proper preasure for this tire?
 

·
Registered
Joined
·
976 Posts
The tire says 50 PSI, why run at 42?
 

·
Registered
Joined
·
137 Posts
I have the same tire...run what the tire says to run 50 psi....it is a rear tire that hopefully you had installed to run in reverse as Metz states on their website....the tire sees forces in reverse under braking and not under acceleration as it was designed....thus mount to run backwards at 50 psi....:eek:
 

·
Registered
Joined
·
2,313 Posts
The tire says 50 PSI, why run at 42?
I did not go check, so I cold be wrong, but tires usually say a "max" pressure, which is different than a recommended operating pressure.

Optimal operating pressure will be vehicle specific. Look at your tires on your car or truck, then look at the sticker in your driver door jam area. The sticker will indicate recommended operating pressures for front and rear, which are usually far lower than the max printed on the tire.
 

·
Registered
Joined
·
158 Posts
Discussion Starter · #11 ·
I have the same tire...run what the tire says to run 50 psi....it is a rear tire that hopefully you had installed to run in reverse as Metz states on their website....the tire sees forces in reverse under braking and not under acceleration as it was designed....thus mount to run backwards at 50 psi....:eek:
It is installed like in accordance to indicated direction. I know there was a big discusion how it should be fitted. I just afraid how tire tread will work on wet while installed in reverse. DOn't you affraid that water will be pumped under the tire? Is it any danger to ride while installed in indicated direction, not reverse, or it just a question of the tire lifetime?
 

·
Registered
Joined
·
2,313 Posts
It is installed like in accordance to indicated direction. I know there was a big discusion how it should be fitted. I just afraid how tire tread will work on wet while installed in reverse. DOn't you affraid that water will be pumped under the tire? Is it any danger to ride while installed in indicated direction, not reverse, or it just a question of the tire lifetime?
You need to see this:
http://www.m109riders.com/forums/showthread.php?t=135118

If you are running it with the arrow, you are the one running the tread backwards compared to Metz front tires.
 

·
Registered
Joined
·
179 Posts
you run any front tire at fifty PSI you'll lowside the first time you take a corner in cool weather....even running hard with 50 PSI in hot weather it will be tuff to keep the heat in the tire...I will get be getting a 160 front soon, in the winter months that sucker won't see above 36 cold....:hot:
 

·
Registered
Joined
·
245 Posts
Finally got my new tires installed Friday about 4:40pm got done by 5:35pm for a total $530 @ twobrotherstires.com in Lawrenceville, Ga .
Results : Front tire great fit and handling WOW! What a change, takes a few turns to adjust to the front but nothing mayor. Plus it looks bad to the bone. Just remember front tire must go in "backwards".

Rear: Looks like a hot Latina with a fine, round & big :edit:ss! Sweeeet!

Tires:Metz front 880 XL Marathon 160/60/Vr18 $228 installed, Rear 260/40/VR18 $317 Pressure recommended by installers Front:40PSI & Rear:40 PSI (Rear w/Passenger 42PSI.

Will Post Pics Today:bigthumbsup:
 

·
Registered
Joined
·
137 Posts
I run it at 50 psi and never hit the pavement....with only 1/4 of the rear edge not used I hardly baby the bike....Do what you wish but hardly think you really know what your tire temp is...........
 

·
Registered
Joined
·
6,984 Posts
I run it at 50 psi and never hit the pavement....with only 1/4 of the rear edge not used I hardly baby the bike....Do what you wish but hardly think you really know what your tire temp is...........
Dude, we are all grown and make our own decisions. 50 psi is ridiculous! 40-42 is what is known by the majority to be both safe and effective. :doorag:
 

·
Registered
Joined
·
2,313 Posts
I run it at 50 psi and never hit the pavement....with only 1/4 of the rear edge not used I hardly baby the bike....Do what you wish but hardly think you really know what your tire temp is...........
Glad you have not gone down, but with 1/4" of your rear not used, you are hardly pushing it.

What I was told about pressure has nothing to do with tempurature, but the "footprint", "contact patch" or amount of the tire in contact with the ground.

You can roughly calculate you footprint by dividing the weight on the tire by the PSI. (I said rough, so before anyone jumps down my throat about the other factors like sidewall stiffness, I am not ignoring it) This was more important in off-roading in soft soil, but it is why you left air out when you take a truck off road.

For easy math, let's say the 9 weighs 800lb and weight is split evenly from front to rear. (of course this is not true and changes based on acceleration/deceleration, but go with it because it makes for easy math)

So, at 40psi, your rough footprint is 400/40=10 square inches

And at 50psi, your rough footprint is 400/50=8 square inches

So, at 50psi, you have roughly 20% less tire in contact with the road than at 40psi.

So, why not take it to an extreme and run 20psi for a 20 square inch footprint? Well there comes a point where the extra contact causes lag and you get enough flex in the sidewall to be less stable.

The optimal pressure is where you get the most contact before it feels sluggish.

I have tried mine as low as 38psi and as high as 45psi and found that I agree with the crowd that suggests 41/42ish.
 

·
Registered
Joined
·
976 Posts
So mount it backwards because Metz says so but inflate to 42 psi because the riders on the forum say so.




ok
 

·
Registered
Joined
·
2,313 Posts
So mount it backwards because Metz says so but inflate to 42 psi because the riders on the forum say so.

ok
No. I do not care who here says what pressure to run it at. The right pressure for the tire/vehicle combo is specific to that combination.

The tire manufacturer sets a max psi, which usually corresponds to intended contact patch size at max load rating. They do not recommend an opperating pressure for any particular application.

If you do the math from 50psi at max load and scale it for actual load when used on the 9, I will bet that it would come right around 40ish, which is why it 'feels right' there.
 
1 - 20 of 26 Posts
Top