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140/70 vs 150/70 rear tire

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38K views 25 replies 16 participants last post by  fpskuji  
#1 ·
Being new to racing there are a lot of things I am still learning. i bought the original size tire for the race. 150/70 I couldnt get comfortable during practice, the bike felt really heavy and I was having to force the bike into the turns. It didnt feel natural. At first I thought since I just got my new cartridges installed maybe they were not set properly. So I took the bike back to the paddock and had our master suspension guy reset everything sag from the bike and rider sag. Everything was correct after checking. I had just bought the set 2 days before the race. $310.00 a lot to spend on tires. Our mechanic told me to stop complaining and buy a 140/70 tire and try it out, he was getting frustrated as I made him check the suspension again. So I bit the bullet and spent another $215.00 for a 140/70 rear. More expensive since I am at the track already. We got the new tire on warmed up the bike took it out on the track and couldnt believe the difference going to a smaller tire made. It was like the bike was on rails, it dropped into the turns with ease. I guess sometimes you need to learn so you never forget. What I should have thought about was I used my N300 140/70 on the bike when I went for my track days. I just couldnt get it in my head that 10mm would make that much difference. TRUST ME IT DOES.

Here is the 150/70 tire after 5 outings in 1 day. No matter how hard I tired I couldnt get to the edge with out the bike feeling like it wanted to fall over.





My 140 tire after 5 outings, 2 practice, 1 qualifying and 2 races. As you can see all the way to the edge.



 
#2 · (Edited)
All very interesting. Can't argue with the results.
Looking at the tread pattern they appear to both be Pirelli Diablo's?

Funny you should bring this up because although I find the N400 turns in OK and is generally very stable, I have been finding it hard to get right over comfortably for some reason. I was also surprised I hadn't ground my hero knobs once yet. Maybe I need to try the 140 when I buy my next rear hoop.
Thanks for sharing.

Late edit: Your tyre wear pattern looks really good BTW, your suspension set up must be pretty good.
 
E
#3 ·
@SDM! one thing I remember from a German Aprilia-Forum is, that the guys over there in the race use the following combination
150/60 rear then the best for the front is the 120/60 (the standard rims are 3 inch front and 4.5 inch rear and yes, even when the standard-rim for the 120/60 is 3.5 inch, the 3 inch is also ok and even allowed from the German TUV, if you know what that means).
The 120/60 lowers the front by 5 mm.
140/70 rear then the better solution is the 110/70 in the front, but all of them say that this combination cannot compete against the series 60 tires.
But at least it depends on you what you like better.
 
#4 ·
Bro your full of information. Thanks for sharing your knowledge. If the tires were cheaper I would try that set up 150/60 & 120/60, that of course will depend on if they are here in country. There is only 1 place that stocks tires for racing and they keep in stock what the racers are using. The other places special order the tires in and its really expensive as they do not offer a racers discount.
 
E
#6 ·
My 2 cts...

I would recommend this, but also want to say since the bike becomes more stable it's not turning into the corners that nimble way like it does with the 110/70 tire.
So to keep this or even make it better at my bike I'd lower the front fork by additional 5 mm (5 mm comes from the 120/60 tire already) and so have the front lowered by 10 mm with the rear shock length extended by 5 mm, which gives a raised rear by 10 mm (please keep in mind that with the uni trak rear suspension there is a transmission ratio from 1:2*).
My rims are 3.5 inch front and 4 inch rear with 120/60 front and 150/60 rear tires.
Please keep in mind that what works for me or what I like must not be valid for you.
And at least everything in case of suspension, like tires, depends on testing, testing and testing until you turn crazy or find the right setup...

* I guess the EX400 is equal to the EX300 and EX250, but for a real value please take the measurement.
 
J
#9 ·
Sorry, don't mean to hi-jack, but I think I decided on the Power RS 120/60-17 & 150/60-17. I was looking at different category tires, and I kind of wanted the Road 5's as I don't do track days yet and the confidence in rain might push me to them again, but I'm not to set on them either. Idk, what do you guys think? Has anyone ridden in the rain with the Power RS before?
 
#10 ·
^^ I like Michelin as well. I have a set of Pilot Road 3 right now.
The Pilot Road is designed for rain. If you like riding in the rain (I love it, no sarcasm), go for the Pilot Road.
I never used the RS. They are supposed to have mote grip on the dry.

I ride mainly street, and some track. I think I'll go for the new Pilot Road 5.
There is no 150/60 though. They make it in 150/70 for the rear, so a bit taller.
And there is no 110. There is a 110/80 but it's a 'trail' tire, which I'm not sure what it is. And maybe 110/80 would be too tall. I don't know.
But for the 120 you have the two options: 120/60 and 120/70
 
#12 · (Edited)
I am sure most of you guys know, but you can't just do some math to calculate the installed height of a tire. With equal "paper sizes", there is a big variety of actual sizes, when installed. Some tires will have a reputation as being "short" or "tall". Same goes with tire weight...big variances.

A 140/70 is, on paper, a 98mm sidewall height.

A 150/70 is, on paper, a 105mm sidewall height.

A 150/60 is, on paper, a 90mm sidewall height.

All of this is theoretical, though, until you mount the tire, inflate to operating pressure, and load it. This is not ultra-critical on the street. But in racing, in can affect your desired gearing choice. Also, rim width plays a part in what you can expect, as well.
 
E
#14 ·
I’m a Pirelli guy.

I’m running 120/70 sc1 front
160/60 sc2 rear

Bike handled great with this set up. The rear tire started to tear after about 100 laps but that’s because I’m still in the stock shock and the rear was moving around a bit


Currently have 150+ laps on a 1.7 mile track on these tires
 

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#15 ·
Tyre wear looks good. Interesting that you find the 160 set up good and SDM prefers the 140. Quite a contrast in opinions.

Hey in what way was your rear moving around? I have a similar sounding problem with my SV race bike. It wags it's tail on corner exit under power. tempting to back off when it is bad. Harder you push the worse it gets. Any thoughts?
 
#20 ·
my recommendation is to check what the local fast guys are running and use that. Our local fast guys are running 110 front / 140 rear on Pirelli and whomever is running MotoAmerica, uses whatever Dunlops gives them

I ran 110/140 on the R3, felt really comfortable, and am staying with the same combination on the N400 race bike as well. Previously, I had 150 rear and didn't feel good for turn in, so switched to a 140 rear and that felt great right from the start. After dialing in the suspension, the 140 rear felt the best by far.
 
#23 ·
Hello, I came across this thread looking for the tire size and options for my new N400 ABS.

Why are you not using the stock specs? Why go a size slimmer, 140?

I have zero motorcycle racing specs knowledge. But I am intrested to learn.

What would be a direct replacement for the front and rear of I will be learning to carve and highway miles for my stock wheels?
 
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#24 ·
MOTOGB, a good place to start is the tire manufacturer's recommendations on rim sizes. Dunlop, for example, says the recommended rim for the 110 GPR 300 is a 3.00", and the 120/60 can run on a 3.00 but the 3.5" is recommended. The 120/70 shows 3.5" as recommended and no alternate rim size. At the rear the 140/70 and 150/60 are both recommended for 4.00" with no alternate rim sizes. The 160/60 can be fitted to 4.5" but 5.0" is the recommended size.

So if sticking to the GPR 300 the 110 front is what Dunlop has designed to run best on the 3" rim and they are fine with either the 140 or 150 on the back 4" rim, but no larger. And it works the other way, you probably won't want to put a 90 section tire on your front 3" rim (that would be more appropriate on a 2.5" wide rim). Tires are designed to have the proper shape when fitted to the proper rim size.

Unfortunately, not all manufacturers are as forthcoming with recommended rim sizes so you may have to look around.

A larger tire is usually also a heavier tire and the weight is out past the rim so there's more of a rotating moment. Just as going from a 520 chain and sprocket to the smaller diameter/lighter 415/428 chain can help with acceleration, so can a lighter tire.

Are you frequently running out of traction due to the tire and not poor riding technique (as in wicking it up while leaned over in a corner covered with water or sand)? You may benefit from a wider tire with a larger contact patch, but you might also stay with the same tire size you already have and bump up to something that has stickier rubber. You could take the tires off of a MotoGP bike and put them on a 125, but that could be too much of a good thing. :)

It might be that you are so blazingly fast and after adding up all the "adds NN% of POWER" claims on the boxes the farkles that you've bolted on came in your bike is so powerful :) that you really do need bigger and stickier tires. Then what you need to do is see what tires are the best fit for the rims you've got. If what you need won't fit on the current rims, then you need to start looking into buying new wheels with the correct rim size for the new tire.

The GPR 300s seem like pretty decent OEM tires for street riding. If you are frequently finding they lack enough grip on your 400, you might want to consider both a tire change and moving off the streets and on to the track, because you are probably riding too hard to be safe on the streets.

Motorcycling can be an expensive hobby. It helps to learn when you really need to spend money on an upgrade and when that upgrade really only gives bragging rights at the local gathering spot. Buy the upgrades that you actually need first.

cheers,
Michael
 
#25 ·
Hmmm I understand. The geometry of the vehicle suspension and wheel travel along with the correct size tire combination is what allows a perfect set-up.

I will certainly need more practice and tire feel... fully understand what causes tire wear, degradation and what is abuse due to riding or improper riding.

I'm looking for a direct replacement to the OEM tires, so that at 3k and on I start to keep an closer eye on my tires to when it will be time to replace.

I am looking at my tires daily, trying to understand the lean angle wears if any huahuahua but mainly to keep the tires checked. I will send a picture when I get my moto back from the dealer first maintanence.

I have used wheel spacers on my M235i to give more grip. Still the tire wear was horrible and I did not feel the car gripping more with the Dinan spring on a M car. So I think that I had too much power for the car package. Which was the truth. Loved that car by the way. I did 1 year of auto crossing and any other event I was able to join. Now I drive a camaro 2.0turbo, stick. A natural un techy car. Which allows me to feel the road, tire and even hear the real sound of the car. (Most cars have fake sound inside the cabin)

I really want to understand the N400 behaviors, its health, consumption and capabilities as a motorcycle.

Thanks for your feedback
 
#26 ·
SDM! said:
Being new to racing there are a lot of things I am still learning. i bought the original size tire for the race. 150/70 I couldnt get comfortable during practice, the bike felt really heavy and I was having to force the bike into the turns. It didnt feel natural. At first I thought since I just got my new cartridges installed maybe they were not set properly. So I took the bike back to the paddock and had our master suspension guy reset everything sag from the bike and rider sag. Everything was correct after checking. I had just bought the set 2 days before the race. $310.00 a lot to spend on tires. Our mechanic told me to stop complaining and buy a 140/70 tire and try it out, he was getting frustrated as I made him check the suspension again. So I bit the bullet and spent another $215.00 for a 140/70 rear. More expensive since I am at the track already. We got the new tire on warmed up the bike took it out on the track and couldnt believe the difference going to a smaller tire made. It was like the bike was on rails, it dropped into the turns with ease. I guess sometimes you need to learn so you never forget. What I should have thought about was I used my N300 140/70 on the bike when I went for my track days. I just couldnt get it in my head that 10mm would make that much difference. TRUST ME IT DOES.

Here is the 150/70 tire after 5 outings in 1 day. No matter how hard I tired I couldnt get to the edge with out the bike feeling like it wanted to fall over.





My 140 tire after 5 outings, 2 practice, 1 qualifying and 2 races. As you can see all the way to the edge.



Click to expand...
You did not change the stock rear rims to fir the 140/70 17 tires right? was planning to buy this for the rear also..
 
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