I just bought a 2008 Road Glide and have put 500 miles on the bike. The prior owner put an 18 inch 2012 Street Glide Rim and tire on the front and left the rear a 16 inch. Since buying the bike and riding it, the handling is difficult to say the least. The front wheel feels like it wants to flop at low speeds. When cornering around a typical 90 degree street corner, in a slower turn around 20 mph the bike feels like it wants to fall into the corner rather than ride thru it. When at 55 mph or up, trying to ride in any corner like a long sweeper what have you, the bike wants to stand up and not lay down into the corner. I have to push in the direction I want the bike to go like always but I also have to pull with the other hand to get it respond and not try to stand up thru the corner. Also, when in those corners, it feels very unstable like the tire is riding on edge and about to break free. It's just plain terrible. I've read other threads where guys are saying this combo handles great? Not a chance, at least not on this bike. I put the stock 16 back on it and it feels fine now, normal riding characteristics. My 2003 Road King I had prior to this bike rode great. I will say that this Road Glide does handle slightly different even with the 16's back on it compared to my Road King. I checked the tire balance at the shop, it's fine. Tire pressure is normal. Tread is good. I checked the rim, it's not damaged or bent. I checked the brake rotors, they are fine. The 18 inch tire looks great except for the handling. It's just not rideable with an 18 incher on the front.

Tires I'm running right now on 16" rims - Front Harley Dunlop Tire MU85B16 M/C 77H / Rear Dunlop Harley MT90B16 M/C 72H


The 18 inch front tire I took off: Dunlop American Elite 130 70B18 M/C 63H

Is there anything unusual going on with these tires? Aspect ratio, width, ply, etc? I understand tires but don't know what the deal is with this set-up to make it handle poorly. It's like the trail is way off like I'm riding a chopper. The 18 inch tire has a slightly lower profile side wall and overall is only 1 inch larger in diameter total compared to the 16 inch. The ride is just awful and unstable with the 18 on the front. Any ideas?

Have you checked the steering head fall away?
If it is too loose it can cause similar issues.
Also, check the wheel bearings and grease in the steering head.
Just a thought.
Best of Luck, let us know how you make out.
Mike U.

It sure sounded like low tire pressure, but you said that's ok. I had a similar experience and found I hadn't snugged the shrader valve down quite tight enough on a tire change. It bled down overnight. Scary feeling! I'll never let that happen again. Keep us updated on your findings.

Are you sure the 18" tire is good ? Just because the tread is good don't mean the tire is.

for perspective, all of the stock front tires for the hd touring line are virtually the same rolling diameter, from the 16'' - 19'' cvo tires. the exception being the 2018 21'' cvo road glide.

there are more than a handful of folks that do not like the ride of the larger, lower profile tires on the front of their bikes. if there is nothing physically wrong with the tire that you have right now, you may just be one of them. though i've ridden all of them and have not been able to tell any significant difference in ride quality between them (i guess my butt is not that calibrated)

I did a search for your front tire MU85B16 M/C 77H and it comes up as a "rear" tire. If it is a rear tire I hope you mounted it backwards to work correctly if it is a directional tire.

The diameter comes out to 25.71 according to Dunlop's website.

In case you have it backwards because the MT90B16 M/C 72H is offered in a front and a rear tire. On the front the MT90B16 M/C 72H diameter is 25.30.

The 130 70B18 M/C 63H has a diameter of 25.28.

There should be no noticeable difference between the 16 and 18 as far as diameter goes. The rake and trail will be approximately the same.

The width of the tires are; 130 70B18 M/C 63H 4.90 inches and the rim should be 3 inches, MU85B16 M/C 77H 5.51 inches and should be on a 3 to 3.5 inch rim.

Not significant difference either, but I believe that narrower front tires do tend to fall into a turn more than wider. Don't think it would be that noticeable with the difference.

There must be some other issue than just tire/wheel size.

The 18 inch fronts that Harley has been using for years have the same roll out as the 17 inch bagger front tires. This causes them to have a compromised contact patch due to the reduced sidewall. I switched my TRX to a 17 inch front wheel at the first tire change. Made a huge difference in the ride and feel. Most noticeable thing was how much I had to change the way I rode in the turns. At first I was constantly cutting the radius down too much. The 17 inch tire needs less input to make the same turn as the 18.

I'm not picturing what you are saying. Sport bike tires have low profile sidewalls and large contact patches. The surface area of the tire is what contacts the road so the sidewall to sidewall profile of the tire is what matters regardless of sidewall height.

I did not yet check the bearings, good point there. The steering head fall away does seem a little loose to me.

I don't know how else to check the tire. I spun it on the front axle with a reference bar mounted close to the rim and the rim seems ok. The tire looks ok but not sure how else to check the tire. It is brand new with only a few hundred miles on it.