Increasing V7 Tire size

[Kiwi Dave]

I'm pleased to report the Avon 140/80/17 RoadRider on the rear of my V7iii Special bought the Speedo to within spec

If the change has brought the Speedo to within spec, there's every chance the odometer will now be inaccurate.

Just saying ......

[denie88]

Thinking of increasing the tire size on my 2013 v7 special.

Searched around but havent found what i am looking for..


Front -
Stock is 100/90-18 thinking of going to 110/90

Rear -
Stock is 130/80-17 thinking of going to 140/80

Thinking of this change to fill out the front fender a bit and to even up the circumference front to back.

Clearance measurements of my Speed Deamons shows that I will be clear, however i am thinking of going to BT45 or Scorpion Trail 2.

Has anyone had experience with this size setup or have thoughts about it?
Thoughts on the Scoprion traill 2?

Cheers

Hi, i'm just wondering do you manage to fit 140/80 for the rear tyre?

[Moparnut72]

I watched a video a couple of days ago where the poster put a 140 on the rear. It just cleared the swing arm, getting it in was a bit of a squeeze. For the front a 110-80 is the right size you would want to use, the diameter is essentially the same as the stock 100-90. That's what I just did, I haven't been able to road test it yet so I don't know if I will have to re-calibrate or not.
kk

[Kiwi_Roy]

I increased the size on my V7III Special
Avon RoadRider MkII 140 80 V17, this made the speedometer more accurate, it was over reading by ~10 percent before.
The Avon barely clears the drive shaft tunnel, just enough to slide a credit card between tire and tunnel

[John A]

In the video I posted, Carcano, it talks about his preferences for narrow tires. I remember a tech rep for Guzzi saying that Americans wanted wide tires. I would usually try to stuff in the widest tire that would fit and I made a jig to true up big block swingarms when I cut out a section and welded on a cover to clear a wider tire. I haven’t done that in decades, especially since the swing arms were changed with a double cardan joint.

[Moparnut72]

I watched a video a couple of days ago where the poster put a 140 on the rear. It just cleared the swing arm, getting it in was a bit of a squeeze. For the front a 110-80 is the right size you would want to use, the diameter is essentially the same as the stock 100-90. That's what I just did, I haven't been able to road test it yet so I don't know if I will have to re-calibrate or not.
kk

I did a short ride yesterday the tendency to follow grooves and seams is gone. My main goal was to get rid of that "feature" of the Sport Demons.
kk

[faffi]

In theory, wider tires deteriorate from handling, as do width differences between the front and rear tire. Wider tires will, provided similar compound and construction, consume more fuel, make steering/change of direction heavier, make the bike less precise, reduce stability, increase unsprung mass and require more lean for any given cornering speed. Tires with varuing width will also force the front and rear wheel to follow different arcs.

Now, we all know that modern frames, suspension and tires can make a bike handle brilliantly with wide tires of different sizes. Still, there are good reasons why Moto3 bikes use very narrow tires; 100/70 front and 120/70 rear. Narrower than most street going 125cc sportbikes. There can be benefits of fitting street bikes with a little narrower tires than stock. I have done so on my V9 Roamer, and I did so on the VS1400 Intruder when I had that. I have also tried oversized tires on a few bikes, none to good effect. That goes for radials as well as bias ply tires.

[twowheeladdict]

In theory, wider tires deteriorate from handling, as do width differences between the front and rear tire. Wider tires will, provided similar compound and construction, consume more fuel, make steering/change of direction heavier, make the bike less precise, reduce stability, increase unsprung mass and require more lean for any given cornering speed. Tires with varuing width will also force the front and rear wheel to follow different arcs.

Now, we all know that modern frames, suspension and tires can make a bike handle brilliantly with wide tires of different sizes. Still, there are good reasons why Moto3 bikes use very narrow tires; 100/70 front and 120/70 rear. Narrower than most street going 125cc sportbikes. There can be benefits of fitting street bikes with a little narrower tires than stock. I have done so on my V9 Roamer, and I did so on the VS1400 Intruder when I had that. I have also tried oversized tires on a few bikes, none to good effect. That goes for radials as well as bias ply tires.

Are you changing rims to the proper width rim for the tire mounted?  Putting wider or narrower tires on the same rim is different than matching rim and tire.  Wider than called for tends to round the profile and narrower than called for flattens the profile. 

[faffi]

Are you changing rims to the proper width rim for the tire mounted?  Putting wider or narrower tires on the same rim is different than matching rim and tire.  Wider than called for tends to round the profile and narrower than called for flattens the profile.

What you write is correct regarding how the rim affect the tire.

As an example of what I have done, the Kawasaki Z750 Zephyr came with a 120/70 front and a 150/70 rear tire stock, with a 3.00 front and 4.00 rear rim. These tires are oversize for the rims, and there have been a number of bikes over the years likewise fitted with too wide tires*. Anyway, I tried the same tire sizes on my son's CB400SF as that of the Zephyr, since they are permissible and since the bikes shared rim sizes, and because these tire sizes a noticeably cheaper than the stock - and ideal - 110/70 and 140/70. The result was a significant deterioration in handling in absolute every way.

Most Japanese bikes before 1983 came with rims too narrow for their tires. The optimum tires size for a typical 2.15in rear rim is 90/90, most Jap bikes came with 120/90, the upper permissible limit. For the 1.85 typical front rim width, 80/90 is optimum, but most bikes were fitted with 100/90. European bikes also often came with less than ideal tire sizes, but usually not as bad as the typical bike from Japan.