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Changing Tire Sizes

118K views 80 replies 31 participants last post by  Christophe.criq 
#1 ·
Figured I'd start a thread so other people can report back what they find using a 120 front and 150 or 160 rear.

I can confirm a 160/60 will fit no problem, which opens up a lot more options for super sticky race rubber and longer lasting sport touring rubber. I won't road test until I get a new set, so hopefully the handling will still be OK.


 
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#5 ·
Also, a couple things I noticed when swapping tires - Michelin is finally balancing their tires (thank god!) and marking them, but there were no weights on the wheel. It only needed one weight, but I found it a little funny that they didn't bother balancing.

Typical of all new bikes I've worked on, there was very little lube where there should be. I greased the axle and put a dab of anti-seize on the threads.

The chain was at the tightest end of spec. That's fine for a big bike, but with 35 hp we probably won't see very much stretch. I put it in the middle of spec and I'll take another measurement in another hundred miles or so.

The rear sprocket has a guard on it. I guess it's on there in case the chain breaks but I don't really see any point to it. Anyone have a good reason why I shouldn't ditch it?
 
#10 ·
I ordered a set of Metzeler M7 RR. Stayed with the 110 for front and went with 150 for rear. I mostly ride around town so probably won't have much input to add. I only decided to change when I rode out around Mt Rainier and never got comfortable with the stock tires. For some reason I think it will make me feel safer with new tires. They also have a promotion for a free Ogio helmet bag with the purchase so I guess it's a double win for me. We'll see...
 
#11 ·
Just mounted the tires I mentioned above. I was surprised how much difference it made. Handles so much smoother and maybe even faster into turns than the OEM tires. I can turn into a street round about so much easier. I'm glad I made the change. Another perk is that the side walls are not as tall and makes it looks much better. I think it's the best $210 I spent on the bike. pics can be found here: https://drive.google.com/folderview?id=0B9cOwgo1DrrXSWpKMnNTcjJWUU0&usp=sharing
 
#15 · (Edited)
No one seems to make a 150/65-17 at the moment.

The speedometer will read 1-2 mph low at highway speeds (40-80 mph) with the 150/60-17 and the revolutions per mile will go up 2.6%, which means slightly faster tire wear.

The new tire is .6 inches shorter, but that shouldn't be enough of a change to negatively affect the bikes steering geometry (specifically the front end rake)
 
#17 ·
So I had a 150 Diablo Rosso II on the track yesterday.
I have to say I think I like the way the 140 feels better. I wasn't able to use all of the tire. Had another ride(way more experienced and faster than me) ride it and even he couldn't get all of the contact patch
 
#20 ·
You're likely not using all of the side of the tread due to the decreased radius of the cross-section of the tire. Follow me here. You're putting a wider tire on the same width rim which originally had a narrower tire. In essence, you're scrunching the wider tire outward, away from the rim, to cause a overall larger diameter tire. Which is why you have to go with a smaller "aspect ratio" (shorter side wall). Now, in scrunching the wider tire outward (to make it fit a narrower rim), think of what you're causing the tread of the tire to do. Is this making sense?
 
#21 ·
Let's say you take the same corner at 80 mph with 140 and 150 tires. For the 140 tire it'll be scrubbing on the edges to make the corner. While on the 150 tires, there's still over an inch on the outside of the tire. Does this make the 150 tire more safer as it's not maxed out? Just trying to figure out which would be best. Thanks.
 
#22 · (Edited)
No. A wider tire is neither better nor "safer" (in my humble [yet knowledgeable] opinion).
Our nimble bike has been designed to use a narrow (nimble) tire. Enjoy and embrace that fact. I've tried fatter tires on my ninja 2-fitty, much to my dismay. I race my bikes. If you wanna race with a fat rear tire, buy a 'Busa or a ZX 12.
...But I guarantee, I'll catch you and pass you in the turns...and you WON'T see me again.
............ ;-)
 
#24 ·
There is NO reason to go to tyres not made for the bike.


150 will not be 'safer', it wont work the rubber properly and generate heat.
Plus the last thing the r3 needs is to be even lower in the ass.
If you are running out of tyre on a 140, have a good look at fixing poor body position.


Bridgestone and Pirelli make plenty of options.
I removed the Michelin Bias ply the very first week and fitted DR2.
 
#36 ·
Reading through this thread to prep myself for new tires eventually... read this and was genuinely confused as heck. "even lower in the ass" ? The R3 is so high in the ass it looks like a freakin' dirt bike sometimes... or am I missing something here?

Probably gonna get 150 in the rear for mine...from a looks perspective it seems better. 10mm ain't gonna make or break it...
 
#25 ·
Changing size really has no pay off

Figured I'd start a thread so other people can report back what they find using a 120 front and 150 or 160 rear.

I can confirm a 160/60 will fit no problem, which opens up a lot more options for super sticky race rubber and longer lasting sport touring rubber. I won't road test until I get a new set, so hopefully the handling will still be OK.


I'm not sure what you're trying to accomplish? There are outstanding tyres available in the 140 and 110 size. The size matches the design of the bike. You do what you want, but you really aren't helping the overall performance of the bike.
 
#30 ·
I'm not sure what you're trying to accomplish? There are outstanding tyres available in the 140 and 110 size. The size matches the design of the bike. You do what you want, but you really aren't helping the overall performance of the bike.
Trying to accomplish buying one set of tires for 2 bikes? If it works, great. If it feels like sh¡t, NBD, I'll go back to stock sizing. It's not "dangerous" and if everyone followed OEM recommendations all the time, we'd all be paying $400 for a set of tires.
 
#26 ·
Figured I'd start a thread so other people can report back what they find using a 120 front and 150 or 160 rear.

I can confirm a 160/60 will fit no problem, which opens up a lot more options for super sticky race rubber and longer lasting sport touring rubber. I won't road test until I get a new set, so hopefully the handling will still be OK.
http://s205.photobucket.com/user/mgfchapin/media/DSCN2182_zps7z5d9g4l.jpg.html
http://s205.photobucket.com/user/mgfchapin/media/DSCN2183_zps6sv9ljtr.jpg.html
http://s205.photobucket.com/user/mgfchapin/media/DSCN2187_zpseqgqwmj9.jpg.html
So to go back to the original post,
Although I'm still running a 110 in the front, I've been very happy with the handling of the 150/60 in the rear. This is the smallest tire size in the tire model I wanted. It grips, has great feedback and is actually faster and easier to maneuver than the factory tires. It could be just me being more confident with the tires. All my riding is on the street, Monday through Fridays
 
#29 ·
I'm with Jesse and t-rav on this one - 140's.

One brand/profile in 150 may be very similar to another brand/profile 140 so sometimes that works out well, but by going 160 you will likely need to lower the rear suspension (decrease preload) and/or lower the forks in the trees to get back to stock geometry - otherwise, handling and/or high speed stability could suffer.

Tire choice is usually based on how you ride or what you want from the bike - appearance, daily commuter, canyon carver, track day/racing.

But, like oil - opinions vary, no warranty expressed or implied, use interweb advice at your own risk
 
#32 ·
I have the Pirelli Diablo Rosso IIs in the same size as the stock. However, the next tires I buy will be the Metzeler M5 which are Z-rate 110/70 for front and 150/60 for the rear. Before anyone makes an incorrect statement, the 4.5 inch rim will accept 150/60 properly. They do cost more than Pirelli, but hey you only live once.
 
#33 ·
You're right, the stock rim will accept a wider tire of that size, but the shape of the new tire will be different from the stock one and you should feel noticeable handling differences. Not necessarily positive ones......

The narrower front tire should give you quicker turn-in on curves when leaning over but will have slightly less traction because it will have a smaller contact patch.

Tire size changes always involve trade-offs and sometimes create adverse handling. To paraphrase Stirz, Tire sizing is part voodoo, part science and part art. Finding the right balance for performance, comfort and safety isn't easy.

Here is a great, short article from Sport Rider (with diagram showing tire shape change from up-sizing) about up-sizing tires on a sport bike. They can explain it far better than I can.

http://www.sportrider.com/does-size-matter?image=0

If you do end up going with these tires and sizes, be sure and report back on how they work.
 
#34 · (Edited)
I'm also changing sizes after I bought the 140/70 Pirelli (ran over something that punctured the front tire). I also have the Metzeler M7 RR 150/60ZR-17 rear and the 110/70ZR-17 for the front. I agree with many opinions, but understand the KTM RC 390 comes with the same sizes and I don't think they would have put the larger rear tire on it, if it had negative affects. Remember, the KTM RC390 is a track bike pure and simple. I did discuss this with the dealer, and his thoughts were agressive riding would have a benefit with the larger tire on the rear for better overall handling and a better ride. The affects of the 180 to 190 is more exaggerated than a 140 to 150 change, especially since both tires fit the wheel the way they are suppose to. I would highly recommend you think carefully about ever upgrading the front tire to a 120, because the wheel is simply too narrow, and not made for that size. The negatives have already been made for the reduction in speed from ex: 65 to 63.3 mph. It has the same affect on the engine as if you dropped a tooth on the small sprocket. It will also help the acceleration in 6th which is a bit too high (somewhat sluggish at 70). As far as buying new tires sooner, please, no one wears out tires on sport bikes, so if it bothers you, maybe you should not make the change. Or maybe look at the FZ 07 which comes with 180 rear and 120 fronts. It is the next best alternative to a sport bike, but remember, the new MT-07 will be here soon. That is probably going to reduce the R3 sales with accessoreis like a movable window, better electronics, hard cases for long trips, etc. It will also put the weight over 400 lbs.
 
#35 · (Edited)
FOLLOW UP TO TIRE SIZE CHANGE: First I bought the standard size in the Pirelli Diablo Rosso II, first finding the ride was better but the bike didn't have the stability I expected with a sharp angle lean. The front tire began to leak with no sign of a cut or nail. The dealer couldn't find it either, although it lost 1.5 lbs over night. I bit the bullet to replace both tires with the Metzeler Sportec M7RR in the 150/60 17 rear and the 110/70 17 front. These are Z-Rated tires and the handling improved significantly and I can only say the tread design was the reason. I also noticed the front tire was somewhat fatter than the Pirelli, even though they are the same size. The downside is the loss of gas mileage to 52.5 mpg at 75 mph. It looks better and it fits the rear rim very well. Mountain Motorsports technician was surprised the oval on the tire was correct, and the side view looked normal. I have no explanation for any of this because my other bike had 180 on the rear and 120 on the front. This is my first experience with the smaller tires. I noticed after a few rides, my chicken stripe was about the same 3/4" on each side. After the tires are broken in, I will get it to 1/4" where it usually is. Now someone might ask why it won't be gone, and that's because I don't ride on the track. I've watched too many guys crash their bikes that wanted to go low on the street, so just call it what it is, a chicken stripe.
 
#39 ·
FOLLOW UP TO TIRE SIZE CHANGE: First I bought the standard size in the Pirelli Diablo Rosso II, first finding the ride was better but the bike didn't have the stability I expected with a sharp angle lean. The front tire began to leak with no sign of a cut or nail. The dealer couldn't find it either, although it lost 1.5 lbs over night. I bit the bullet to replace both tires with the Metzeler Sportec M7RR in the 150/60 17 rear and the 110/70 17 front. These are Z-Rated tires and the handling improved significantly and I can only say the tread design was the reason. I also noticed the front tire was somewhat fatter than the Pirelli, even though they are the same size. The downside is the loss of gas mileage to 52.5 mpg at 75 mph. It looks better and it fits the rear rim very well. Mountain Motorsports technician was surprised the oval on the tire was correct, and the side view looked normal. I have no explanation for any of this because my other bike had 180 on the rear and 120 on the front. This is my first experience with the smaller tires. I noticed after a few rides, my chicken stripe was about the same 3/4" on each side. After the tires are broken in, I will get it to 1/4" where it usually is. Now someone might ask why it won't be gone, and that's because I don't ride on the track. I've watched too many guys crash their bikes that wanted to go low on the street, so just call it what it is, a chicken stripe.
Losing 1.5 overnight could just be tire heat change. 3-5 lb difference between cold and hot is not uncommon.
 

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#38 ·
Not going to quote everyone here, but I have a few responses to some of the above posts.

First, don't compare a bias ply tire to a radial. A radial tire is just going to handle better because of how it is constructed.

It really isn't a positive to have a Z rated tire. Z rating means the tire manufacturer has just tested the tire up to a certain speed (depending on where the Z is placed and if there is a Y or W at the end, it varies between 149 mph and 186 mph) and that the tire can withstand that speed for, at least, 10 minutes. Z rating also means the tire will have a stiffer construction, I don't mean rubber, but rather, the inner structure of the tire.

According to the "Wheel and Tire Performance Handbook" by Richard Newton, "...there is no direct relationship between the size of the tire and the size of the footprint. The contact area is determined by load divided by tire pressure"

Having a Z rated tire on a R3 is like putting 275/35 tires on a Prius.

A 10mm change in the rear ride height can have a huge difference in handling of a bike. You change the geometry of the bike by raising or lowering either end of the bike. It was common practice to raise the front forks of an SV 5mm to 10mm in the triple clamps to get a better geometry for turn in. Rear shock height was then 13.75" - 14". Sure, you could go with something else, but those measurements really worked for most people. Not just on the track either.

The R3 doesn't have a 4.5" rim. It is 4". Putting a 160 on the rear will really pinch the tire and square it off. If you need to picture this, make a half moon shape with your hands by touching your fingertips together. Then slowly move your wrists together and watch what happens to the curve of your fingers. That is what is happening to a larger tire when you put it on a smaller rim.

As for the KTM having a 150 rear so it must be better because that bike was designed for the track holds no water. The KTM has a different geometry than the R3. That tire may just work better for that particular geometry set up. It doesn't mean it will also work for the R3. Plus, if you have ever visited the RC390 forums, you will see some of the racers switching to the 140 for better turn in on the corners.

If you really need proof that bigger isn't always better, just look at the guys running Moto 3 in Moto GP. Many times those guys are carrying more corner speed than the guys on the big 1000cc 200+ hp bikes. Yet the Moto 3 tires are only 120 on the rear and 90 on the front! Remember, Moto 3 bikes have more HP than the R3, yet those guys are almost dragging their elbows during races.

I guess if you want to throw your money away on bigger tires go for it. I will stick with the 110/140.

Sorry for the rant. >:D
 
#57 ·
Not going to quote everyone here, but I have a few responses to some of the above posts.

First, don't compare a bias ply tire to a radial. A radial tire is just going to handle better because of how it is constructed.

It really isn't a positive to have a Z rated tire. Z rating means the tire manufacturer has just tested the tire up to a certain speed (depending on where the Z is placed and if there is a Y or W at the end, it varies between 149 mph and 186 mph) and that the tire can withstand that speed for, at least, 10 minutes. Z rating also means the tire will have a stiffer construction, I don't mean rubber, but rather, the inner structure of the tire.



Having a Z rated tire on a R3 is like putting 275/35 tires on a Prius.

A 10mm change in the rear ride height can have a huge difference in handling of a bike. You change the geometry of the bike by raising or lowering either end of the bike. It was common practice to raise the front forks of an SV 5mm to 10mm in the triple clamps to get a better geometry for turn in. Rear shock height was then 13.75" - 14". Sure, you could go with something else, but those measurements really worked for most people. Not just on the track either.

The R3 doesn't have a 4.5" rim. It is 4". Putting a 160 on the rear will really pinch the tire and square it off. If you need to picture this, make a half moon shape with your hands by touching your fingertips together. Then slowly move your wrists together and watch what happens to the curve of your fingers. That is what is happening to a larger tire when you put it on a smaller rim.

As for the KTM having a 150 rear so it must be better because that bike was designed for the track holds no water. The KTM has a different geometry than the R3. That tire may just work better for that particular geometry set up. It doesn't mean it will also work for the R3. Plus, if you have ever visited the RC390 forums, you will see some of the racers switching to the 140 for better turn in on the corners.

If you really need proof that bigger isn't always better, just look at the guys running Moto 3 in Moto GP. Many times those guys are carrying more corner speed than the guys on the big 1000cc 200+ hp bikes. Yet the Moto 3 tires are only 120 on the rear and 90 on the front! Remember, Moto 3 bikes have more HP than the R3, yet those guys are almost dragging their elbows during races.

I guess if you want to throw your money away on bigger tires go for it. I will stick with the 110/140.

Sorry for the rant. >:D
you are right and the motorbike physical explanation is- if you have a thinner tire you dont lean as many angles as if you would be at same speed with a bigger tire.

so you can take corner with higher speed at same leaning angle.
 
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