Another 10K and Replace

[Rio Wil]

Last July before leaving for Alaska, I installed a Pirelli P4 205-65-16 for the trip.  It now has just over 45K including about 500 miles of Alaska's famous gravel roads.  The remaining tread depth  as measured is kinda what is expected on the sides, but the inner two measurements seem odd.  The crown on the road would make the left side wear faster than the right side (.205 vs .220) but the inner wear seems reversed. I measured several places around the tire and it is pretty much the same as indicated in the picture. Perhaps the tread is just built that way but the difference of .025 is a lot for what I would consider a symmetrical inner tread. Any way, I couldn't be more pleased with the life of the tire and I have never had any uncertain moments on the road in wet or dry traction despite the relatively high tread wear number (780). It has a nice stiff sidewall and I run 42 psi, hence the inner tread wear (but who cares at 45k  and another 10k expected.) This tire seems to be getting scarce, mine had a date code of 2007 when I installed it 18 months ago.....so, what to do next time???? It has been plugged once (from the outside) and I am not uncomfortable running another 10k this way.  I am not inclined to do a 205-60 because of the rpm increase, if I could find a 205-75 it would be great, another 250 rpm drop would be nice....always looking for the 6th gear!!!!!!!

My friend just finished dropping a cool $30k in a S&S 122 powered HD lookalike , I might have to drop down to a 205-50 to get the acceleration needed  to keep him respectful of the Valk's stock performance....although it would might make first gear almost redundant/unusable.

Since I am on my second scotch, here is a story of a near miss today. (remember it's my second scotch).  I had stopped at a bank for atm cash and was ready to pull out into the street (making a left turn)......traffic from the right was good, from the left was a little close but not a concern.  Rolled on the throttle a bit, slipped the clutch and picked up the left foot I had been balancing on.....the engine dies as my pants cuff catches on the kick stand and brings it down far enough to kill the engine.  Realizing what happened, I freed the cuff and quickly kicked the stand bask into a raised position, but a fraction of a second was lost....I saw out of the corner of my eye the oncoming pickup hit the brakes, not hard, but enough to know my action was causing him a conflict. I completed the turn and the pickup continued on.  A seemingly innocent action of just pulling into the street......could have gone badly wrong. You can never let your guard down or become complacent about an action.    PS.... an 18 year Glenmorangie scotch is just perfect to remove the chill from a 37 degree day.......well it started out that way, but any excuse will do to ride or to have a little sippy!!

[John Schmidt]

Dropping to a 205/60/16 would give you approx. a 92rpm difference comparing the two sizes at 3000 rpm.

[Smokinjoe-VRCCDS#0005]

Just curious have you took the wheel off in those 45,000 miles and done maintence on the final drive splines and pinion cup / driveshaft ?

[Rio Wil]

Yeah.....every 12-15K....just can't get away from that, huh.

[GOOSE]

WOOOO...I was thinking the same thing that Joe was.

[Rio Wil]

Dropping to a 205/60/16 would give you approx. a 92rpm difference comparing the two sizes at 3000 rpm.

John.....it seems to me that when I went to the 65 series from OEM, it dropped the cruise rpm by about 250. Also seems the 60 series is about the same height as the OEM so maybe 92 rpm is about right.....thats why dropping down to a 50 series might be necessary to get the acceleration needed to kick his 122 inch butt.....   I would hate to live with the difference in cruise rpm tho...
The difference in tire rev's per mile between a 50 and 65 series is about 76, if we know the overall drive ratio say in 5 gear we can calculate the engine rpm difference....

[Ricky-D]

I run a 205/55/16 and the increased rpm's used to bother me but that annoyance has faded over the years.

The wearing of the center being greater than the outer bands has been explained to be consistent with the flat tread design and not related to pressure at all.
The explanation being that the center is always in contact with the pavement while the outer part of the tread is not always in contact with the pavement.

Again, this is regardless of pressure whether it be low or high.

It amazes me the way the tire presents itself, even after 45k miles.

***

[Valker]

I run 26# in my HydroEdge 205/55-16. This is a picture of it at 40,000 miles. I haven't noticed uneven wear at all. I'm not exactly sure why. On my Tourer, 75 mph indicated is 3300 RPM indicated.

[Rio Wil]

I was looking at a simple way to calculate engine rpm based on the rear tire size.  It's easy enough to calculate/find the tire revolutions per mile, then multiply that by the final drive gear ratio, them multiply that result by the 5th gear ratio then by any reduction in the transmission.  But, I don't understand the specs in the manual:
primary reduction    1.591
secondary reduction 0.971
final reduction           2.833
the fifth gear is           .805 

I'm guessing that 'final reduction' is the ring and pinion in the final drive but what is the meaning of primary and secondary reduction?

Tire rev per mile (761) times final drive (2.833) times (trans reduction?) =engine rpm

However I cant get close enough to the indicated rpm at 60 mph (corrected) for it to be a valid calculation........what am I doing wrong?

I don't know how you can run 26# and the tire not squirm around especially in getting on a freeway on ramp  with a tight curve, mine scared the hell out of me with only 30 lbs due to a nail that was about to be discovered.....swear I could feel the sidewall buckling!

[Valker]

Not sure either, Rio. All I know is mine is super stable at almost any speed (starts to wander at something over 100mph so I just don't go there anymore). Not sure if the wandering is the tire or the miles on everything else. Mine takes full power acceleration with no issues in any gear. Scraping pegs creates no instability. I usually travel with me (about 300 lbs) and about 70-75 lbs of gear. I have Progressive 440s with HD springs with about 100K miles on them.

[Smokinjoe-VRCCDS#0005]

I was looking at a simple way to calculate engine rpm based on the rear tire size.  It's easy enough to calculate/find the tire revolutions per mile, then multiply that by the final drive gear ratio, them multiply that result by the 5th gear ratio then by any reduction in the transmission.  But, I don't understand the specs in the manual:
primary reduction    1.591
secondary reduction 0.971
final reduction           2.833
the fifth gear is           .805 

I'm guessing that 'final reduction' is the ring and pinion in the final drive but what is the meaning of primary and secondary reduction?

Tire rev per mile (761) times final drive (2.833) times (trans reduction?) =engine rpm

However I cant get close enough to the indicated rpm at 60 mph (corrected) for it to be a valid calculation........what am I doing wrong?

I don't know how you can run 26# and the tire not squirm around especially in getting on a freeway on ramp  with a tight curve, mine scared the hell out of me with only 30 lbs due to a nail that was about to be discovered.....swear I could feel the sidewall buckling!

I'm so glad things like this never cross my mind.

[BamaDrifter64]

[/quote]I'm so glad things like this never cross my mind.
[/quote]

Me too neither, Joe....if I thought about stuff like that, my head would probably explode...

Dave

[Rio Wil]

Actually you guys bring up another little quandary. Since the diameter of the tire is used in calculating the rev's per mile, are they determined using the loaded or unloaded radius.....probably makes a difference in .250 inch in radius, thus affecting rev's per mile. So, we can't even trust the rev calculators available on the internet, they don't specify either condition. If this is so vague, how can we trust the important things like proof rating on one's favorite scotch bottle or the density of the steel wool on 0000 wool......it could actually be 0001 and we would never knowwwwwwwwwwwwwwwwww.  AH CRAP.....I just ain't getting into this so......how about a MERRY CHRISTMAS and leave it at that...  

[salty1]

Merry Christmas Rio!  Leave tire questions and like discussions for another day.   

http://i389.photobucket.com/albums/oo332/dreamchaser07_2008/Santa_Claus_On_A_Motorcycle.jpg

[Smokinjoe-VRCCDS#0005]

Merry Christmas Rio!  Leave tire questions and like discussions for another day.   

http://i389.photobucket.com/albums/oo332/dreamchaser07_2008/Santa_Claus_On_A_Motorcycle.jpg

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[salty1]

Thanks Smokin, I needed that!



Santas Workshop after a hard night

[etiwandablues]

I was looking at a simple way to calculate engine rpm based on the rear tire size.  It's easy enough to calculate/find the tire revolutions per mile, then multiply that by the final drive gear ratio, them multiply that result by the 5th gear ratio then by any reduction in the transmission.  But, I don't understand the specs in the manual:
primary reduction    1.591
secondary reduction 0.971
final reduction           2.833
the fifth gear is           .805 

I'm guessing that 'final reduction' is the ring and pinion in the final drive but what is the meaning of primary and secondary reduction?

Tire rev per mile (761) times final drive (2.833) times (trans reduction?) =engine rpm

However I cant get close enough to the indicated rpm at 60 mph (corrected) for it to be a valid calculation........what am I doing wrong?

I don't know how you can run 26# and the tire not squirm around especially in getting on a freeway on ramp  with a tight curve, mine scared the hell out of me with only 30 lbs due to a nail that was about to be discovered.....swear I could feel the sidewall buckling!

I was researching options for reducing gear ratio & rpm and came across this thread and several others. I didn't understand some of the info in the service manual (primary and secondary reductions) and couldn't make a calculation that would match what I see on the speedo & tach while riding. So after looking at the manual for longer than I care to admit, I've found that the primary reduction of 1.591 refers to the reduction between the crankshaft and the transmission main shaft. The secondary reduction of 0.971 refers to the reduction (or in this case increase) between the transmission counter shaft and the output shaft.  The primary and secondary reductions need to be included in calculations. If you consider the transmission to be everything between the crankshaft and the driveline, then 5th gear ratio goes from 0.805 to 1.25. The final reduction of 2.833 is the ring & pinion in the final drive.

I have an 03 std and when I'm at 75 on the speedo, GPS says ~71mph, and the tach is at or just over 3500rpm. I run an Avon Venom R (measured equiv to 25.5 in dia) and when I calc what Rpm should be at 71mph I get about 3300 rpm. So from all this I conclude my tach is reading about 200 rpm high. So my speedo is off by 4 mph and my tach by 200rpm and I'm still wishing I had a little lower gear ratio.