My stock rear tire is about gone with less than 7k on it. My front has miles to go of course but I'm going to replace that as well.

I'm going to go the the Metzelers MME 880s. I know it's ok to have a radial in the rear and a bias in the front. Its has to be ok because my stock tires are set up that way.

Here's the stock tires that are on my bike now.

Front: Dunlop D401F 100/90/19 M/C 57H (bias)
Rear: Dunlop K591 160/70R/17 M/C 73V (radial)

I understand that radials have a lower profile than bias, and that if I go with the Metzeler 170 radial for the rear my speedo will read that I'm traveling faster than what I really am. So here are my questions.

If my stock rear is also a radial will my speedo running faster?

if not....

does that mean a bias rear will it affect my speedo?

Does Metzeler make a 160 rear radial? I looked but couldn't find one.

I'd like to get this resolved pretty quick because I decided today that I'm riding up to Pisgah Forest this Saturday with a few friends. It'll be about a 400 mile day trip and I'd rather not ride my worn rear tire in those mountains.

My local indy has Metzeler front 100/90/19 (bias) selling for $126 and a rear Metzeler 160/70/17 (bias) for $182. I know I can probably get them cheaper online but I may not have time to wait for shipping.

Any help would be appreciated. Thanks!

 

Never heard that radial automatically have lower profiles - thought that was a factor of the aspect ratio?

The only real answer to your question is this - if the overall diameter of your new rear tire is different than the diameter of the stock tire, the speedo (and odo) will be affected. But so what? Most metric bikes I've owned had speedos that read close to 10% slow at 60. Compared to my GPS, my ElectraGlide is about 2 mph slow at 60.

The small impact of a slightly shorter (or taller) tire isn't really going to matter much, IMO.

Hey, did you ever get those saddlebags? Waiting on your review and pics.

 

You're right, not automatically. But between the Metzeler 160's and 170's I read that's the case. Anyhow, I'm just curious to see how it affects my ride.

As far as the saddle bags, well, when I was searching on that website I had a few bags in my cart that I was considering, so when I went to order the tourmasters I wanted, I had to delete the rest of the things in my cart. I deleted the wrong ones and received the wrong bags. Anyway, I sent them back and then got busy with work and wasn't on here for about 3 to 4 weeks. By that time I forgot all about that thread. Someone did buy them and start a thread with photos. Here's the link,

https://www.hdforums.com/forum/dyna-...etty-good.html

 

just grab those metzelers and don't look back.... you'll love the handling difference from the stockers. I actually have the night dragon on the rear, and the metz 110 on the front of mine, but i dont' think there is a huge difference in handling. Both made by pirelli. I love em.....and thats not a bad price if you need em quick.

any change in speedo reading would be somewhat minimal i would think, but i could be wrong. If it was a significant thing to consider, I would also think the manufacturer would either volunteer to state such a thing, or maybe be required by law to post that info.
As well, you would probably have heard it by now from other riders talking about it or sharing their experiences.
Something else, to consider.....if you have a new tire, and wear it down it's a lower profile than new, so does that noticeably change your speed?
I've often wondered the same thing..just hard to imagine more than a mile per hour or so of a change. I'm sure there is a mathematical formula for figuring it out exactly. I would like to see it too, but at this stage before your trip, I wouldn't stress one bit over it....get geared up, enjoy your trip, and be safe.

I'm jealous

 

Thanks Glydiator. I saw some of your older posts on tires. Very informative. Actually, you're the one who got me over thinking this tire ****. LOL I'm going with what my indy has and get the Metz 160 for the rear and the 100 front. I'm not worried about 1/8 of an inch or so wider. Not enough difference for it to matter....tpo me anyway. Thanks again.

 

BTW. I need to make a correction. My stock rear tire is NOT a radial. My eyes must be going. It reads B but in my dim garage it looked like an R. Just thought I'd clear that up before I get ripped a new one. lol

 

ha ha...thats sort of why I said don't worry about it. I did a ton of research and in the end, the differences were little, but articulate.
Good to hear that the posts are at least being read though. I hope they help.

For me, the metz's were probably the best "Overall" of the tires i researched. I chose the night dragon so I could get the actual facts on it, as the pirelli company wouldnt disclose it...for whatever reason. I have my theory, but won't go into that now.

In a few days, you'll be focusing on how awesome your bike handles, and how good of a time your having instead of anything else.

hells yeah

 

Here's what bicyclist do to make sure they keep their bicycle computer/speedo calibrated. Mark a spot on the tire and position the bike with the mark dead center on the ground. With the bike weighted by the rider weight (it helps to have a friend), roll it forward one revolution. Measure the distance. Bicycle computers come with a "cheat sheet" so you can re-program your computer to match that number and then your speedo is calibrated. In your case just do the same thing after you mount the new tires and compare the numbers. Then you'll know if there is gonna be any differences in the rolling distance which ultimately affects the speedo and odometer reading. Obviously tire pressure plays a part in this calculation as well.

 

Well, let's just do it mathmatically cuz i'm too lazy to chalk a line on the pavement.

Dunlop K591 Rear tire:
inflated diameter= 25.8 inches
deepest tread depth= 8/32 (1/4 inch)
Which would be .5 inch total diameter decrease if bald.

Circumference of Dunlop K591 (fully inflated) tire = Pi x Diam. 3.14 times 25.8 in.= 81.012 in.

Circumference of Dunlop K591 (fully inflated, worn completely bald) tire = Pi x Diam. 3.14 times 25.3in.= 79.442 in.

Difference in travel per revolution= 1.57 in.

1 mile = 63360 in.
revolutions per mile new = 63360 divided by 81.012 = 782.106
revolutions per mile worn = 63360 divided by 79.442 = 797.563

Difference in number of revolutions per mile = 15.457

Percentage of increase of revolutions from new to bald = 1.9% increase

Travelling at actual speed of 70 mph (which is bad on a bald tire) -- add 1.9% to your speedometer.

Speedo reading with new tire = 70mph
Speed reading with bald tire = 71.33mph

In actuality, you probably wont wear the tire bald so the difference would be even more negligible.

If your tire sizes are different new, then you can use this formula to figure it out.

The Metzeler ME880 170/17 is 25.16 vs. Dunlop K591 at 25.8

both have 8/32 tread depth.

so the difference of these two tires is .64in......very close to the new/worn differences of the same tire. You could estimate it at about 1.5 mph difference new between the tires new.

But!....Just for fun, lets check the difference between the Dunlop new 25.8 and the Metzeler worn 24.66.
It is a whopping 1.14 inches.

Thats gonna be more significant... twice the decrease in size so just guess at 3mph overall. But you would start at 1 or 1.5 mph difference and end up at 3mph difference.

again though, you won't go completely bald on the metzeler....or at least I hope.

Also, you would have to know for sure if Harley calibrates their speedo's precisely with a new Dunlop K591 on the rear.

This may all be way off.....I'm a bigger engineer/math poser than I am a biker poser so take it with a grain of salt.....and a beer or twelve....or both salt and beer

I welcome any and all corrections to my off the cuff analysis as I think there are many to be made, lol.


I do still stand by my original statement though: enjoy your trip and be safe.

 

George, I think some good prices have been had from motorcycle-superstore.com. You can try a local indy shop. Heck, just for giggles, ask your dealer what they'd charge for a set of ME880's. Get a baseline price and then go from there.