Tyre Sizes


Scim77

Member
I agreed with the sentiments expressed by "Gregjet" on 03/04/2015. I have always felt that Yamaha have opted for style over function with the big fat tyres fitted to the MT-07. I think the bike would feel much more nimble if narrowed tyres were fitted.

Even on the original rims, it might be possible to fit the next smaller width size without altering the overall circumferences too much or the ride heights and rake angles. Would 170/60/17 happily replace the 180/55/17 rear and a 110/70/17 on the front instead of 120/70/17. Does any tyre manufacturer make such a size?

Has anyone been brave enough to try this? I would be interested in your views.
 
D

Deleted member 20

Guest
I would say no need to change front tyre dimension.
MT07 rear rim is 5.5". FZ1 has 6" and 190 tyre. TDM900 has 5" rim and 160 tyre. I guess a 170/60 would work on a 5.5" rim and yes there are tyres made in that dimensions with same speed and load rating as 180/55. The 170/60 has fractionally larger circumference, help reduce speedo error.
 

gregjet

New member
I agree that the front doesn't need to change. I would like to try it because it would allow me to lower the head tube a bit more and get a bit more front weight ( with a lower mudguard) and it would be a bit lighter.
I actually have a spare 160/60 and at some stage when I am feeling particurlarly frisky I might try and fit it just to see if it fits. I have to do it entirely by hand so I will need to be really motivated...That would be my preferred tyre size, though the wider rim will lower the inflated profile a bit. Without finding a narrower rim to fit I think we are stuck with the 170/60. Still there are some really nice tyres in 170/60.
I know there are motard slick sizes in 160/65 that would be worth a play but I don't have any anymore. That would probably come pretty close to perfect for a track bike.
I wonder if a TDM or a trx wheel would fit????
 
D

Deleted member 20

Guest
Throwing some numbers into Excel tell me that 160 width on 5.5" is not a good idea, 170 width is a stretch already. Sample Yamahas with different 17" rear rims, good luck gregjet trying them all out for fit on the MT07. Please report back when you are done testing :)

View attachment 2443
 
Last edited by a moderator:

b00f

Member
Why not go a 180/60? This would create sharper lean angles (tyre dependent)

I just threw a 180/60/17 Q2 on, and is much taller than the stock PR3/4 I had on there, and creating much sharper lean angles, and gives great "chuckability"
 

Scim77

Member
Raising the rear end (or lowering the front) will indeed make the bike turn more easily. But adding yet more rubber to an already grossly over-tyred rear wheel will hinder the bike's ability to turn, due to greater gyroscopic inertia. The heavier the wheel/tyre combination, the more reluctant the revolving mass will be to change axis angle.

The current 180.55 ZR17 73W is capable of handling bikes that are nearly twice the weight of an MT07. This overkill is a pity. When my current rear tyre wears out, I will go to 170.60 ZR17, since I don't fancy the expense of changing rims. The rolling circumferences are almost identical (within 1%).

I think that 110.70 ZR17 would just fit the 3.5" front rim and definitely provide quicker turning.
 

Phil_B

Moderator
I'd just stick pilot road 4s on. I have PR3s on my MT and PR4s on my street triple and the 4s are much taller and narrower even in a matching 180/55 size. They turn in quickly!
 

Scim77

Member
Hmm. That's odd. I would have thought that the profiles should be the same, having identical size and aspect ratios. Do you think that the Street Triple might have a different profile of rim, that holds the tyres differently?
 

nobull

New member
If you change tyre sizes and are involved in a serious accident then you are screwed. Why bother? Adding rear preload will sharpen the steering with no effect on insurance, and if you want a really fast steering bike then you should have bought a more sports oriented machine anyway, surely?
 

gregjet

New member
" If you change tyre sizes and are involved in a serious accident then you are screwed. Why bother? Adding rear preload will sharpen the steering with no effect on insurance, and if you want a really fast steering bike then you should have bought a more sports oriented machine anyway, surely?" changing to a 170 should have no effect on accident investigation , in Aus at least. So long as the tyre is weight and speed rated accordingly. The tyre is the wrong profile , for a start. It adversely effects the handling at lean, especially when paired with a front profile. It is just plain too big. Too big is as bad as too small for different reasons. If you only ride in city traffic upright, it would make no difference. But if you get into an emergency situation and have to rely on big lean angles and BALANCE front rear this stock tyre combo will lose the front way before the rear bigtime. There wil be no safe slide margin.
Please do not make the ridiculous statement " the Yamaha engineers know what they are doing" This rim/tyre choice is a STYLE choice by the marketing dept to make it look like a bigger bike. There is no handling justification for this huge, heavy badly profiled tyre.

And30ers, Thanks for that list. I will have a look around for some data on the FZ6 and the TDM and see if I can make one of them fit.
 
D

Deleted member 20

Guest
gregjet,
I don't get that 180/55/17 rear would fuck up the MT07 balance making it unsafe at lean?
All bikes > 500 cc has 120/70/17 fronts, paired with a rear tyre from 150/70/17 via 200/55/17 (1299 Panigale S) to 240/45/17 (Ducati Diavel).
Smaller bikes with 110/70/17 fronts have rear tyre in range from 130/70 to 150/70.
Basically only 2 front dimensions for all rear combinations (excl. 120/60/17 front that sits on older Monsters 600's etc.).

I'm not saying 180/55 is perfect for the MT07, using 160/60 would have been better (less weight, enough grip, faster transitions), but dangerous, no.
 

Scim77

Member
If you change tyre sizes and are involved in a serious accident then you are screwed. Why bother? Adding rear preload will sharpen the steering with no effect on insurance, and if you want a really fast steering bike then you should have bought a more sports oriented machine anyway, surely?
I will speak with Carol Nash about your valid concern regarding potential insurance issues and report back when I get an answer.

No bike is perfect. Most are made balancing a trade-off between costs, marketing and engineering. It is always possible to improve or personalise a bike to some extent, although often at disproportionate expense.

I prefer upright roadster-style bikes, like the MT-07, and have no interest in sports bikes. The KTM 690 Duke handles far better than the Yam, in my opinion. It is lighter, more stable in corners and more flickable. But I could not live with the restless power delivery under 4000 rpm or the nervous gearbox. I road-tested several bikes before buying but opted for the Yam because it ticked most of the boxes. It still does.

We all contribute and follow this forum because we fundamentally like the MT-07. I am one such enthusiast. But I also recognise that there are some things that I might be able to tweak, to make the bike nicer for me. A less bulky rear tyre is one of them.

Thanks to all for the combined wisdom that circulates through this forum.
 

gregjet

New member
And30ers I am refering to the tendency to run out of tyre at the rear before the front. I don't have anywhere I can ride hard enough around here but when I lived in Townsville and still had my F800R which had the same tyre combo I would routinely feather off the edge of the 180/55 and the front would still have chicken stripes. The back would decidedly nervous until you heavily accelerated even power slid it. Then it would start to overheat and get sloppy. Now the BM had 90HP and had the reserve to power slide. The MT does not. I still maintain that the tyre combination on this bike has the potential to be unbalanced enough to be dangerous when pushed.

Scim,
My girlfriend has a KTM 690 duke and much prefers it. I had to do a lot to tame the aweful fuelling but she now loves it and doesn't like the MT. Me I like the MT better as the power delivery is smoother it allows you to start accelerating earlier in the corner. Sally had a huge accident sometime ago (way before the KTM) and is much more tentative out of corners , so the big hit when it gets more upright is more her thing.
 

Scim77

Member
Insurance for non original tyres

If you change tyre sizes and are involved in a serious accident then you are screwed. Why bother? Adding rear preload will sharpen the steering with no effect on insurance, and if you want a really fast steering bike then you should have bought a more sports oriented machine anyway, surely?
In response to the point raised by Nobull regarding an Insurance Company's stance on non-original tyres, I have just received a reply from my own insurers, Carol Nash. Provided that the rim remains the original size, then they are happy about my using different tyre sizes. But if I want to change the rim size, then they need to be informed and would consult their underwriters again.

Maybe Gregjet will have reported back by the time I need a new back tyre. A 170/60/ZR17 should be no bother at all and would improve handling somewhat. A 160/60/ZR17 would be my preferred choice but might be too nipped on a 5.5" rim. I will probably leave the front alone, especially since it will last twice as long as the rear.
 


Top