73 FLH Speed Grip rear tire wearing flat

[Twister the fitter]

I'm looking for some answers as to why my 73 FLH might be wearing my rear "speed grip" tires to a "flat" profile across the tread. I've had 2 new tires in the past 2 years, about 2,000 miles on the first one and the new one this year has around a thousand or so. I've completely replaced (to spec) the rear wheel bearings before installing this years tire and have even upped the tire press by 10-15lbs. ( I carry a lot of tools and spare parts in the saddle bags ). I've checked the swingarm for play and haven't found any at all. PLEASE help if you can !!! Twister the Fitter/Tim

[joe fxs fxr]

I'm not sure I understand your question. All motorcycle tires wear to a square cross section, because we spend most of our time going straight. If you ride like squid on mountain roads, you will get some wear to the edges, but still not as much as the middle.

[Twister the fitter]

Thanks Joe for the reply ! I do a lot of my riding here in the mountains of central PA, just not laid over like a "road racer", ha ha. I'm just puzzled I guess, as to why the tires are wearing so "quickly", that's all ??? 2,000 miles on tire, year before last and around 1,000 miles last year. Do you think that I should switch over to the new radial design type tires they offer today, such as the Dunlop D404's ? Thanks, Twister

[T. Cotten]

Well, Twister,...

Even back when Goodyears were real tires, they still wore flat on the rear, and to a bit of a peak on the front. Much more so if you pulled a hack, so rotation was more than prudent.
(It seemed like every time I lifted the garage door, somebody had erased more of my rear tire, and that's back when they wore like iron. Still got a crawlspace full of double-white take-offs...)

But now everybody swears a hard tire is dangerous.

Manufacturers won't take a gamble in court against wide-spread beliefs, right or wrong. Soft, gummy, and evaporating is in style.

....Cotten
PS: I have no experience with any 'radials' on a motorcycle, sorry.
(But I did run a huge "re-cap" for a season. Rode fine, but scared me to death if I looked down and saw how the tread wobbled badly. Still got it, 'cuz it looks cool on a bobber under the street lights.)

[kitabel]

Not enough air pressure

[Twister the fitter]

Thanks for that info Mr. T. Cotten, Twister

[Twister the fitter]

Thanks Kitabel ! Would you have a suggestion as to what air pressure might work ? HD manual calls for 25lbs in rear and I'm currently running around 15lbs (40lbs total) above that, just trying to overcome that "flatness wear". Twister

[Architect]

What tire exactly are you running? Are you using old Goodyear Speedgrips or cheap Shinko look a like tire? 25# sounds low for a swing arm bike, 40# might be a little high. But again, what tire are we discussing?

[Twister the fitter]

Cheap Shinko look-a-likes ! The bike came with a newer set of them on and when the rear wore flat during the first year riding 2,000 miles I replaced it with another to match the good front and rode 1,000 miles last year with about as much "flat" wear as the previous 2,000 mile tire. Would you happen to know if the "Coker Classic" tires are any better ? I'd get a set ($502.00/Jeg's) of them, as I'm running a wide whitewall. I'm trying to keep the original "speed grip" look without switching to the Dunlop D404 tread look just yet ! Thanks for your help, Twister

[Architect]

I had nothing but problems with those Shinko double white wall tires. First rear tire was "out of round" (per Shinko), they sent me a replacement, was not much better. Riding solo at highway speeds she would start a death wobble that was not always easy to get stopped. Those tires in my opinion are for trailer queens or bikes that are never going over 40 MPH. As I ride my FLH a lot (our go to two up bike) I gave in and got a set of Dunlop American Elite tires with the skinny white wall. Still looks fairly correct but night and day difference in the handling of the bike. I wish I had done that in the first place and not wasted two years messing with the Shinkos. Good luck.

[Twister the fitter]

Thanks Architect, that's EXACTLY how my bike acts !!! The "death wobble" you refer to is the same and I didn't realize where it was coming from till now, THANKS so much !!! I replaced the entire rear hub bearings and internals, new tire and balancing last year, thinking they were worn and causing the wobble and wear. I'm definitely gonna give those Dunlops a try, you saved me, my friend !!! Twister

[Architect]

I had the wheel and tire on my truing stand. Rim was at most 1/16" out, the tire was almost 1/4" out!!!!! As stated replacement was not much better. I tried 15 PSI all the way to 40 PSI, still wobbled. With the Dunlops, she will do 75 MPH all day long, solo or two up, no wobble. If anyone tells you they are good tires, ask them if they ever took the bike over 40 MPH. I was going to get the Dunlop D402 that has been on Harleys forever, my Indy convinced me I wanted the Elites, they have proven to be an excellent tire.

Glad I was able to help, good luck with new tires.

[otis71]

I’ve always ran 5.00 x 16 tires on my vintage bikes so what I’m adding is just what I’ve heard others say: bikes that were designed for 5.00 don’t handle right with modern 5.10 tires because the profile is different. Can anyone confirm or deny this?