On Wednesday, September 19, 2018 at 5:21:05 AM UTC-7, Theodore Heise wrote:
On Wed, 19 Sep 2018 07:33:24 -0000 (UTC),
dave wrote:
On Wed, 19 Sep 2018 01:40:46 +0000, Theodore Heise wrote:
I've used mostly Continental tires for over 20 years and
nearly 100K miles of road riding. Recently I got a half dozen
Ultra Sports (700c x 25), and after putting a new on on the
front noticed a definite bounce as it rolls. I've tried three
now, with the same results. The wheel is very true and round,
with no flat spots.
This review includes a video that shows what miine look like:
https://www.amazon.com/gp/customer-r...SIN=B00HPSCDBE
On top of that, they are damn hard to mount on the wheels! I've met few
tires I can't get onto the rim with just my hands, but these are almost
impossible to mount even with levers.
The bead is probably not seated right. I have the same problem
with Schwalbe 20 inch tires. The rim manufacturers and the tyre
manufacturers are just a dinkleberries in disagreement. I am on
my third rim and tyre combo. Still tight AF but will just fit.
Deflate the tyre. Lube up the bead with some soap. Inflate to
"Holy mother of god! How much?" PSI It may decide to pop into
its seat properly.
Or it may not. Good luck. 
That's possible, but seems unlikely for *three* different tires
mounted at least five times. Also, I inspected the seating of the
tires pretty carefully, and there is no apparent difference in
tire placement around the rim. On top of all that, wouldn't the
bead either seat or blow out on riding for hundreds of miles?
Your options are a defective tire or a tire that is not beading. Some tire and rim combinations a just bad, and you can get a tire that will not bead without soaping, beating, prying, pumping, etc., etc. Untreated, the tire will not bead no matter how long you ride it. Ultra Sports are an unhappy combination on my Sun CR18 rim which has a shallow rim well. They're tight, but they do bead and are round. I quit using them because of poor sidewall durability. I never had one that was mismanufactured.
-- Jay Beattie.