Fitment Issues with "SP" spec tires on a "CR"?

[shoeman1952]

hello all,
just wondering if there are any adverse effects if i were to install "SP" spec tires (stock is 120/70 and 170/60) on my "CR" (stock is 120/60 and 160/60).

(assuming that the larger rear tire would fit on my 4.5 inch rim.)

thanks,
the shoe

[Desmomaniac]

nope, no issues at all. in fact it was recommended to run 120/70 profile front tire on the street as there were many complaints about 120/60's allowing dinged rims from potholes and speedbumps. but the low profile 120/60's do look good. the 4.5" rear rim will allow for a 170/60 but not a 180/55. if you want 180/55 you'll need a 5.5" rear wheel.

[shoeman1952]

thanks very much

got my 900ss/cr last april w/4600 miles on her, and original tires. plenty of tread but ............... i pushed the front end last summer and i'm still blaming the tires () so new sneakers are in the works.

in the shop this week for an early valve check/new CaCycleworks belts at 5600 miles, then my usual disass/check/clean/lube/fiddling for a few weeks on the entire bike. can't wait to start blasting around southern vt and western ny this summer.
bobp

[Desmomaniac]

if those are the original shoes then they need to be swapped out; they eventually "dry" out out, get hard, and lose grip.

yes definitely anxious to get out... been couped up to long in ct this winter. hope to soon hit western mass & southern vermont too, but looks like it'll be another month and half before that happens.

[shoeman1952]

yup, tires are old and gotta go. got the bike last april and took it real easy all summer. pushed it a little bit and whoops!

btw, a new duc dealer is opening right up the road and i'm stoked. was going to follow the bcm techs further west in nh but "cyclewise / ducati vt inc" has just opened it's doors in middlebury vt. full service shop, nice showroom, test rides are encouraged. knowledable, personable, friendly, fair.

am picking my bike up this morning for it's first valve check at 5400 miles(no record of the initial 600mile). quoted at $330 and came in at $356 (2 openers and 2 closers needed). i supplied the cacycleworks belts and removed the panels.

later,
bobp

[FunkZ]

I put 120/70 fronts on my CR at recommendation of a shop. First thing is that the taller profile will require modification of the fender and using different bolts to give enough gap so that the tire doesn't rub. Second is the 120/70 is a heavier tire and between weight and profile it causes a slower turn-in. After riding both and the hassle of making it fit I would just stick with the 120/60.

[shoeman1952]

thanks for the info.

my calcs show the 120/70 front tire would be 1inch taller than the 120/60, while the 170/60 rear would be 1/2inch taller than the 160/60. total change would be 1/2inch taller on the front, and should result in a slower turn-in.

i'll check front fender clearances tonight, again many thanks. spring up here is still a long ways off, am still researchin'.
bobp

[Desmomaniac]

now that i remember it; i did have some tire contact on the stock front fender but it was minor rubbing on the trailing edge of the fender. occasionally the fender would flex and contact the tire there. it definitely wasn't a constant contact issue but it was very close for me. i later replaced the stock fender with a carbon one that provided ample clearance and never had issues afterwards.

considering that the 120/70 was stock on the ss/sp i'm not sure handling impacts would be enough for me to differentiate. but then my bike's front end has changed so much over the past 14 years from the original non adjustable marzocchi's that it would be hard to say. i've transitioned from the marz-suckies, to 996 adjustable showa's, to ohlins internals for the showa's over the years. the rotors have gone from brembo to braketech and the wheels have transitioned from brembo three spoke, to brembo five spoke, and now marchesini forged aluminum.

i remember ended up swapping to the taller profile because i had two minor dings in the three spoke rim before the first tire change. that and simply because that size was more available in the local shops. the lower profile is probably fine for use on groomed tracks but may not be ideal for public road use.

[shoeman1952]

many thanks for the fine comments, much appreciated.

i believe i would be able to feel the difference in tire heights, 'cause when i first got the bike the forks were 15mm down in the triples. the bike felt a touch unstable for me (5-6, 155lbs) at lower speeds. raised the forks until flush w/the tops and much better overall.

new thread for a quick clutch pack question.............

[El Gladiateur]

Go for the 120/70. Nevermind slight rubbing, time and wear will cure that.
I had rubbing in my front fender on my 998, with OEM Michelin Pilot Sport tyre.

[Desmomaniac]

Originally Posted by shoeman1952

thanks for the info.

my calcs show the 120/70 front tire would be 1inch taller than the 120/60, while the 170/60 rear would be 1/2inch taller than the 160/60. total change would be 1/2inch taller on the front, and should result in a slower turn-in.

i'll check front fender clearances tonight, again many thanks. spring up here is still a long ways off, am still researchin'.
bobp

your math is right but your reference points aren't. height changes are relative to the axle not the entire diameter. if you switched from 120/60 & 160/60 to 120/70 & 170/60 the over all change on the front would be less than a 1/4". only if you left the rear 160/60 would you see almost a 1/2" height change with a 120/70 front tire. iirc you can easily drop the triples on the forks 10-15mm to make up most of that difference if handling is a concern.

on a side note, strongly recommend changing out the suspension before spending money on trinkets. the cr suspension after '95 was bare bones. ohlins rear shock allows for adjustable ride heights. about all you could do with the non adjustable marzocchi forks was change springs, add spacers for preload, and change oil. changing the forks isn't as easy as the shock but the reward was worth it imo.

[shoeman1952]

yes! my reference was to overall diameter instead of to the axle, thanks very much!

have spent some time shopping for tires and noted little difference between the 160/60 and 170/60 pricing, usually <$2. with a stock front tire and moving to a 170/60 rear, the rear would be raised only 6mm, so am leaning in that direction since bridgestone says a 4.5inch rim is ok.

as part of my winter refresh, have spent some time recently on electrical connections. i removed a few zipties near the steering head (right side) that was causing some tightness of the wiring loom when nearing full-lock. i recall some early monsters had issues w/broken wires due to restricted flexability here. i also disconnected/wiped clean most electrical connections (especially the troublesome rect ones, it had to be removed to get at all of them) and lubed with dielectric grease. same treatment at the headlight plug; for the last 1000 miles or so i have run a 100w H4 w/no issues. imo, many overheating problems may be caused by corrosion.

anyhow, thanks again.
bobp

[shoeman1952]

phew! finally made my choice of tires and vendor after some searching, and ordered a set of bridgestone bt021's from jakewilson.com for $193 delivered - no tax. went with stock front size and the slightly larger 170/60 on the rear, overall a good choice for me. rated as a sporty-touring tire, i think the bt021 tire will be fine, as my riding is somewhat less aggressive as i near the big 6-0. the days of burning thru 2 fronts and a rear every 6 months on my f4i are long past (well maybe 4 years ago).

at my age some folks think i should be out riding a 'wing, but f that