Scuffed in a new front tire

[FJmonkey]

Last weekend I mounted and balanced a new front tire in the garage. I think I went about 1000 to 2000 more miles on it than I should have. My last ride the weekend before really beat me up in the corners. I was having to counter steer to keep her in the corners. I noticed this coming back from the last WCR, I thought my luggage made some changes to the soft rear shock and altered the geometry slightly. Not so, they were badly Veed off on the sides.



Not sure if the detail will show the flat spots.

The new tire.



Nice and round profile, seeing the tread depth (or lack of) is another clue how worn the front was. 8200 miles, I should have changed it when I put the second rear on. Too lazy, not any more, the difference was awesome. It feels like she just floats into the corners with nothing more than looking into the corner. The man (Monkey) and machine are now synchronized in pure cornering bliss once again.

Up at Newcomb's ranch had a nice tidbit of Yamaha Porn. An R71



Check out the air intakes...




The orange does not come through in the photo properly, it is fluorescent orange, a real eye catcher.

A good but short ride for the day, all scrubbed in and ready for the next ride in sunny SoCal....

[racerrad8]

Mark,

I am looking at the picture of your tire and I believe you are not running enough air pressure. With the RPM fork valve set up you have in your forks, you need to be running at or very near the tire manufactures recommended pressures. (no more than 2lbs less than recommended)

Mike Ramos stopped into today as he had the dreaded blind nut that holds the shifter bolt break out of the frame happen to him on the trip from Redding to Walnut Creek last night. The bike was stuck in forth gear the whole way and he still managed to get almost 40mpg. Heck we even pulled the clutch cover to check the clutch due to the 4th gear starts and it looked great still too.

Anyhow, I was working on Pat's bike when he got there and since he needed to get that fixed to be able to ride home, I asked Mike, since he is good with a gigantic screwdriver, make some carb & valve adjustments to Pat's bike while I fixed his; he gladly accepted the job of working on the shiniest bike in the RPM shop.


But since I saw your post about your front tire, I snapped some pictures of Mike's Michelin Pilot Power 3 tires that he installed prior to leaving for the ECFR. The tires currently have over 7000 miles on them which is pretty well split between highway and twisty miles as he took the Capt' Ron style route to the rally and slabbed it home. Both tires are pressured to the manufactures recommended pressure rating on the side of the tire and Mike thinks there is at least another 4-5k left on them.

Front:


Rear:


As you can see there is no "V"ing or cupping to speak of on either the front or rear.

The other thing about all of this is the rear shock and fork oil now have 22000k on them. The shock is coming off at 25k for the first rebuild since the valving was settled upon and we are going to dump the fork oil and see how it looks. No fork seal leaks in 22k either.

Mark, and all others who have installed the RPM fork components or RPM rear shock, air up those tires; eliminate the tread deflection and get the maximum contact patch on the road surface for the best traction and the most miles from a set of tires for slabbing and better fuel economy due to lower rolling resistance.

Randy - RPM

[Pat Conlon]

Uuuuuh, Randy......so tell me....what exactly is Mike doing with that giant screw driver....?

Adjusting my USD's?

[racerrad8]

Uuuuuh, Randy......so tell me....what exactly is Mike doing with that giant screw driver....?

Adjusting my USD's?

No no, he is dialing in the carbs.

But he did say something about "those forks..."

Randy - RPM

[FJmonkey]

I have been running 34psi in the front on my Conti Motions 17" radials... Is that too low? I seem to get the same result from the Avons I ran at the same pressure. I think my problem is I don't ride enough slab to balance out the other angles of riding. The Crest is really my back yard, corners are my normal FJ meals...

[Pat Conlon]

........Both tires are pressured to the manufactures recommended pressure rating on the side of the tire....

I also have PR-3's and they are great tires....I'm away from home now so I can't go out and check, what is the maximum pressure rating on the sidewalls of those Michelin's ?
46 psi? Something like that?

[FJmonkey]

46 Maybe 38?

[ribbert]

Both tires are pressured to the manufactures recommended pressure rating on the side of the tire and Mike thinks there is at least another 4-5k left on them.

What tyre pressure does he run? Michelin recommend the bike manufacturers pressures.

[Firehawk068]

My front tire wore the same way as Mark's...................................Except I went a little further than he did  



I always run my tire pressure around 40psi (front and rear)

I knew the tread was getting low, and toward the end of the ride it started feeling like I was riding on a thin layer of sand in the corners................I took it really easy the rest of the way home.
I tried looking up how many miles I had on it, but I couldn't find it.................I know it was on there for around 3 years though.........

[FJmonkey]

My front tire wore the same way as Mark's...................................Except I went a little further than he did  



I always run my tire pressure around 40psi (front and rear)

I knew the tread was getting low, and toward the end of the ride it started feeling like I was riding on a thin layer of sand in the corners................I took it really easy the rest of the way home.
I tried looking up how many miles I had on it, but I couldn't find it.................I know it was on there for around 3 years though.........

Holy crap!!!! You get my nomination for steel braided scrotum award....

[racerrad8]

The Michelin tires on Mike's bike are rated to be 42psi and that is what I told him to run and is running. I can only make tire pressure recommendations based on the RPM fork valves and lighter springs and no other combinations.

Mark, put the air pressure to the max pressure listed on the side wall and you will get better tire wear, performance and mileage.

Randy - RPM

[Pat Conlon]

Try as you may, you can not convince me that the contact patch is larger on a front tire @ 42psi.

[racerrad8]

Try as you may, you can not convince me that the contact patch is larger on a front tire @ 42psi.

It is not larger, but there is no internal tread roll due to under inflation. With those stiff spring being used by all other other fork valve manufactures and USD forks with stiff springs you are using the low tire pressure as a spring to soften the ride.

I do have a lot experience with tires & suspensions regarding tire contact patch to to asphalt, and that was part if the design process of my fork valves.

Tread roll; the air pressure within the tire cannot maintain the full contact patch due to the leading edge of the contact patch gripping the asphalt. Thus the center of the contact patch distorts due to low pressure and pulls away from the surface due to low air pressure not be able to maintain the shape of the contact patch.

You can see it in Mark's tire, the center is pushed up and the majority of the tire is deflected causing the tire to wear the way it did.

I never said it make the contact patch bigger, it just uses.more of it.

Randy. RPM

[racerrad8]

Here is a rudimentary picture to illustrate what happened to Mark's tire.

The tire manufacture(s) design the tire based on the pressure listed on the side of the tire. They have to have a standard measurement of air pressure when designing the tire to see what the tire will do under load. For someone to believe, especially today with today's tire technology compared to 1981-1993, how could you ever justify using the motorcycles "manufactures" suggested settings. Today's tire were not around when the bike was made, so why would you use the Yamaha's recommend setting, did they design or test the bike with the tires you use today?

Mark's tire is definitely under-inflated as the sides have worn more than the center, the same contact patch of the picture above regarding under-inflation.

And also...

By looking at the pictures posted of Mike's tires with 7000 miles on them, you cannot see that same wear characteristics, so the tire pressure has a direct effect on the wear & performance of the tire.

Randy -RPM

[Mike Ramos]

Good evening everyone,

First of all, it appears that the gentleman from RPM has posted the wrong picture of some ignorant idiot with upside down glasses working on Mr. Conlon's motorcycle.  That is not yours truly; all who know me (from the Rally's) will verify that I am not much over 4' tall [Windancer where are you?].  The actual picture that was taken at the palatial R.P.M. shop this very day has me standing on a milk crate along side my own bike.  

However, I do admit to utilizing the improper size screwdriver while attempting to tighten the carbs into those rubber boots that attach to the engine while Randy was working on the shift lever bolt on my bike.  Only two of the four boots were torn & nearly destroyed; however after consulting with Skysomebody I sealed up the tears with silicone sealant.  I was assured that the new improved silicone sealants will be impervious to heat.  I just hope Randy doesn't notice 'cause he is so meticulous.  I sure hope the owner doesn't discover it...

It is true that the shift lever bolt "malfunctioned" just as has been described on this Forum - and I attempted to repair it while on the road.  I did not have any tin foil on hand nor any super glue so invoking The Reverend's name I prayed...  but that did not help either...   Anyway, since my folks will not allow me to have a cell phone until I am twenty one,  I limped into the RPM shop and without prior notice and fortunately Randy was there.  

Boy, was he surprised to see me...  mumbled something about not wanting to be disturbed...   anyway, taking time away from the engine installation he installed the new shift lever bolt and soon ushered me out the door...

Have fun,

Midget