One of my tail lights on my tourpack went out (#198 12v 98/3cp), and I replaced it with a (#1157), and everything works and seems fine.
I couldn't see any difference in the bulbs, but I thought I would ask to make sure. Thanks

 

Same thing happened with me except it was one of the front turn signals. I put in a #1157 and it works fine. I don't know why H-D uses the #198 bulbs, but the #1157 seem to be a perfect replacement.

 

Found this on another site, posted by a "cleonard" (credit where credit is due):

The 198 bulb is the "heavy duty" version of the 1157. The 198 is a little dimmer, but more robust (vibration resistant). If you can't find a 198, the 1157 will work fine. Some auto parts store sell a 1157LL. The LL is for long life. It's nothing more than a relabeled 198.

More robust/a little dimmer suggests a heavier filament, Nice to know though. 1157 is certainly much more readily available.

 

The 198 bulb is the "heavy duty" version of the 1157. The 198 is a little dimmer, but more robust (vibration resistant). If you can't find a 198, the 1157 will work fine. Some auto parts store sell a 1157LL. The LL is for long life. It's nothing more than a relabeled 198.

That's good info Krow, because both Walmart and Autozone here have the 1157LL for about $3 bucks for two. No telling what the dealership charges.

 

The brake light filament on the 198 is brighter then the 1157. 29 Watts versus 27 Watts.
See the below link for all the specs. I also use the 1157LL since they seem to be more widely available. Even Walmart carries them.

http://www.gelighting.com/na/busines...ll_catalog.pdf

 

The standard 1157 will last a long time on a bike.

 

I wonder if you could tell the difference if you had one of each side-by-side...

 

Yeah. If you replace one side and not the other, will it be noticably brighter?

 

Actually, I can speak to that issue...

On my 2011 UC, one of the front running/turn signal bulbs went out...that is, the running light part of it...turn signal still worked. I pulled the bulb and discovered it was a 198. I had some 1157's handy so I used one. As far as the running light portion is concerned, I can't tell any difference looking at them side-by-side.

The spec mentioned earlier had to do with the brake (turn signal) part of the bulb. By turning on the 4-way flashers on the bike, it looks like that both are the same brightness. So, I think the 1157 is a good replacement for the 198. The 1157LL might be even better, as far as, vibration resistance.

 

Well, I did a test to see if there was a difference in brightness with the brake engaged. I have the 198 on the left, and the regular 1157 on the right in tourpack. I tied a long string to the front brake where I was well behind the back of my motorcycle and engaged the brake, and as far as I can tell, there's no difference in brightness with either the tail light, nor the brake light.