Topic: flat spot on rear tire

[750K2]

hi all - i've had my 750 stored for two seasons and recently uncovered it for this coming riding season.  got it all running on the stand when a friend noticed that the rear tire now has a flat spot, presumbably from sitting in one spot for so long.  will this flat spot clean up with some gentle riding or am i in for a new rear tire?  is there some way to remove this flat spot on my own? this tire is new when i got the bike and has very few miles on it. thanks!

[TwoTired]

Sometimes they return to round.  Sometimes they don't. 10 PSI over inflation could help stretch it back.   Might helps us answer if we knew the tire type/brand.  Was the tire without air while it was sitting?

Cheers,

[mattcb350f]

Sometimes they return to round.  Sometimes they don't. 10 PSI over inflation could help stretch it back.   

Yea, it depends how big of flat spot too. If it's an old tire and a real big flat spot I've seen them develop cracks in the rubber at the edge of the flatspot. Might help to leave it in the sun if you can, heat might soften it up.

 Matt.

[750K2]

tire is a dunlop K627.   tire was not stored flat.  someone told me that i could heat it gently with a torch and the air pressure would help to reform it.  sounds kinda shaky to me though.  tire isn't cracked and otherwise is in good shape.  thanks TT

[Geeto67]

Tire + Torch = junk tire

Best thing for it is a little extra pressure and some sunshine.

[merc2dogs]

no torch if you want/need to apply heat because of cold weather use a hair dryer which while it gets warm, it's a gentle heat.

  Using a hair dryer it's not much different than having a tire sitting partially in the shade on a sunny day.

  Hair dryer is also great for cold days when the bike/mower/snowblower etc won't start, heat up the carbs and she'll normally fire right up.

Ken.
 

[TwoTired]

tire is a dunlop K627.   tire was not stored flat.  someone told me that i could heat it gently with a torch and the air pressure would help to reform it.  sounds kinda shaky to me though.  tire isn't cracked and otherwise is in good shape.  thanks TT

You're welcome.
OK, I think that is a bias ply tire, non-radial.  I can't find the cord material type.  But, if it is just the rubber deformed and not the cords stretched, it should recover it's shape in time with use.

Heating the tire isn't a bad idea.  Open flame IS a bad idea.  I hair dryer is ok, but a heat gun develops higher heat, still without flame.  As with most tools, the more powerful the tool, the more skill is required to use it properly.  I'd sure try over inflation and some 50-70 MPH cruising before applying heat to the tire.  Also, mark the tire for the flat spot on the side wall.  Then don't park it on the flat spot part until it resumes proper shape.  If doesn't return to round in 1 or 2 weeks, then it's replacement time.

Cheers,

[TwoTired]

One more thing, check that the tire bead is seated properly on the rim.  There is a often a line molded into the tire near the rim.  It should appear equidistant from the rim all the way around on both sides of the tire.

Cheers,

[Tower]

Dunlop K627 is an old-compound, nylon wrap on nylon and steel side chord, bias-ply tyre.  Its a K591 with white lettering and been around a long time now specifically redesigned for low-speed scooters/bikes.  About the same quality as Cheng Shin.

This tyre provides a soft ride due to the nylon ply.  As TT says if the chords have stretched, it will permanently develop a flop.

My suggestion is underinflate to about 25 PSI, then go for a 25 mile ride (just not too fast).  The tyre should be nice and hot when you return.  Elevate the wheel and wait until cooled down.  Flop should be gone. However, a new tyre in probably in your future...perhaps...Bridgestone Spitfire? newer compound, bias ply, soft but grippy ride, similar value priced.  or arguably, how about the best Bridgestone bias-ply, their BT45?

Edit: Don't get me wrong - I have no particular interest in Bridgestone, just comparing to a comparable design more modern tyre.

[75modrat]

I know I do lots of dumb stuff. I only wear a T-shirt and Jeans in the summer. My preferred footwear is chuck taylors. Not only do I not run a chain guard but I cut the mounts of so there will never be one on there again. I dont have turn signals or a horn. Yet somehow, the idea of using questionable tires strikes me as dangerous and not worth the risk. Whats a tire cost? I didnt pay much for my Pirrelli MT66's.

Now that I am done writing this I really dont see the relevance. Feel free to completely disregard it all. Ha!

Frank

[chrislib]

Might want to check the rim runout as well. The tires on my bike have less than 500 miles on them, BUT I installed them back in 2001-ish  . I bought the bike did a bunch of work (tires,chain,sprockets etc) and only rode it about 500 miles or so (tires still have nubbies on em). When I started messing with it this past winter I also found the tires to be "not concentric", I also found the rims to have a fair amount of runout, that, combined with the wasted, self centering stem bearings made the bike NOT so fun to ride (hence why it has sat). I recently (last night) finished truing the front rim and don`t ya know 90% of the hop/wobble in the tire is gone also. I hope to get started on the rear tonite so i can R&R the SA for some "laying of the hands" by one of our very own. Sooo, ck the runout, even if it`s out by just a bit every little bit helps IMO.

[LoopsAndLogic]

How did you true your front rim?? Cause I'm having a hack of a time with mine

LL

[chrislib]

I attached a dial indicator to the fork leg, altho with a good eye you could prob fab up a wire pointer to get it reasonably close. I still have it set up on the fork, I`ll try and get a pic later.

[Steve F]

Just ride the piss out of it for a good hundred miles, and the heat from riding should set it back to normal.

[750K2]

i'll try all of the above..then probably spring for a new tire if things don't pan out.  thanks for the great suggestions!! and i promise..no open flames.
frank

[754]

1 quick burnout in 2nd gear will put enough heat & centifugal force into it..

 If you need help, I am available....

 Hope it has a good clutch...

[dusterdude]

gee 754,thats mighty white of you.

[754]

Nobody EVER said , "Ride it like its Yours"

to me or my buddies..more than once!!

A guy I used to ride with went on a Triumph test ride in Vancouver BC. He asked if he could run it hard, they said ride it like its your bike!! It was group ride.

So he did! After he did a burnout they came unglued all over him.. BANNED him from any more test rides.  If it cant handle it.. what good could it be..

 And this guys has very nice clean bikes, in fact  at least 3 of them are in the Deely Museum.