Why do people use different tire sizes than stock...? ? ?

[Huzo]

Where else would you want the HP to go?

HP doesn't "go" anywhere... It's torque that's applied to the road and the equal and opposite vector drives you forward. HP is a mathematical expression of the Rate of doing Work. Forcexdistance / Time. (Again)

[Huzo]

I understand the allure of "upgrading" your vehicle to some people, however I must disagree about the cause and effect of owners modifying their vehicles driving manufacturers' evolution.

Sure, it happens every now and then, but I doubt it would be a primary motive in evolution of design.

Me, I am happy with a stock bike, stock tires and engine/fueling/ignition, shocks etc.  Other than windscreens and luggage etc I have never been so unhappy with a motorcycle as to change it from basically stock.

You are obviously comfortable in your own skin and don't feel like you have to buggerise around with something to express yourself. Hats off to you Have a look at the last bike conceived in Meriden versus the first one from Hinckley. A basket case of un saleable good bikes to instant road and sales success. The new bikes were styled towards Japanese super bikes with head down ass up stance and wide (ish) tyres. We are all victims of stylists when we sign the cheque in the showroom, it just becomes the "new normal"

[SmithSwede]

Boy, we sure are into basic physics lately!!! 

Can someone explain why it's harder to countersteer with a tire having a larger contact patch if your engine has a 270/450 firing order?   

Assume the tire is inflated with nitrogen, and assume the torque tube is unobstructed and drains all excess torques away.   

[oldbike54]

Boy, we sure are into basic physics lately!!! 

Can someone explain why it's harder to countersteer with a tire having a larger contact patch if your engine has a 270/450 firing order?   

Assume the tire is inflated with nitrogen, and assume the torque tube is unobstructed and drains all excess torques away.

 Yeah , and just mow much HP does a horse make ?

 Dusty

[Arizona Wayne]

Why do people use different size tires than stock?    Because some think outside the box. 

[Rough Edge racing]

Good article , the doubters all need to read it . Thanks .

 Dusty

 The article has no absolutes and does mention situations where a larger tires does offer more traction for drag racing...However, for the street bike example  I will yield to your opinion until I find proof you are incorrect....

[twowings]

Can't you guys just accept that what a Moto Guzzi does is MAGIC and complete understanding won't add to the experience...do your maintenance, watch that oil, ride it regularly, and have a beer once in a while...this ain't rocket science, it's a TRACTOR motor...peace out!

[Perazzimx14]

HP doesn't "go" anywhere... It's torque that's applied to the road and the equal and opposite vector drives you forward. HP is a mathematical expression of the Rate of doing Work. Forcexdistance / Time. (Again)

Everything in the universe is a potato or not a potato!

[radguzzi]

Honestly, I would never presume to know more than the engineer who designed my vehicle.

This is my point and was at the outset. 

I have experienced larger tires than those that came on Guzzis, SPs, EVs and others...  they just seem to steer in a truck-ish slow manner with tires that are larger than those they were designed for.

Even just putting a 120 rear vs a 110 on an 80's Tonti has made a difference.. to me.

Best,
Rob

[Arizona Wayne]

This is my point and was at the outset. 

I have experienced larger tires than those that came on Guzzis, SPs, EVs and others...  they just seem to steer in a truck-ish slow manner with tires that are larger than those they were designed for.

Even just putting a 120 rear vs a 110 on an 80's Tonti has made a difference.. to me.

Best,
Rob

I guess a bad difference to you?   Whereas to me it makes a good difference.  So then our expectations of X bike must be different. 

[radguzzi]

I guess a bad difference to you?   Whereas to me it makes a good difference.  So then our expectations of X bike must be different. 

I guess... an odd difference for me, I just did not care for the feel, I tried but have always gone back to what I consider the proper size tires.  I do not road race though.

What is "X" bike...?

Best,
Rob

[Arizona Wayne]

I guess... an odd difference for me, I just did not care for the feel, I tried but have always gone back to what I consider the proper size tires.  I do not road race though.

What is "X" bike...?

Best,
Rob

Right now my X bike is CX100 or Convert.  Then there's my 750 Breva that had a 130/80 but now has a 130/90 rear tire , or my Suzuki VX800 that had a 150/70 but now has a 130/90 rear tire.   They all have taller rear tires for longer lasting rubber & taller gearing.  As for handling, I feel little difference, but do get more ground clearance.

[Kiwi Dave]

They all have taller rear tires for longer lasting rubber & taller gearing.

Does your speedometer reflect this taller gearing?

[Arizona Wayne]

Does your speedometer reflect this taller gearing?

With these changes my speedos are more accurate than they were with stock gearing.  Most MC speedos are 7-10% fast compared to real mph.  This also gives you more accurate mpg and odometer reading.

[Huzo]

Boy, we sure are into basic physics lately!!! 

Can someone explain why it's harder to countersteer with a tire having a larger contact patch if your engine has a 270/450 firing order?   

Assume the tire is inflated with nitrogen, and assume the torque tube is unobstructed and drains all excess torques away.

Nah mate, no idea !

[Huzo]

Can't you guys just accept that what a Moto Guzzi does is MAGIC and complete understanding won't add to the experience...do your maintenance, watch that oil, ride it regularly, and have a beer once in a while...this ain't rocket science, it's a TRACTOR motor...peace out!

You leave any time you want, but we like it ! You'd make someone a good wife TW, just can't stand to see a guy enjoy himself !

[Xlratr]

With these changes my speedos are more accurate than they were with stock gearing.  Most MC speedos are 7-10% fast compared to real mph.  This also gives you more accurate mpg and odometer reading.

Most speedos are optimistic by around 5%. Legally they are allowed to show too fast (up to a limit), but under no circumstances may they read too slow!
But odometers are usually more accurate. A Speedo correction (like can be done in Guzzidiag or with bigger tyres) likely means the odometer shows less distance covered than reality.


Sent from my iPhone using Tapatalk Pro

[elvisboy77]

You are obviously comfortable in your own skin and don't feel like you have to buggerise around with something to express yourself. Hats off to you Have a look at the last bike conceived in Meriden versus the first one from Hinckley. A basket case of un saleable good bikes to instant road and sales success. The new bikes were styled towards Japanese super bikes with head down ass up stance and wide (ish) tyres. We are all victims of stylists when we sign the cheque in the showroom, it just becomes the "new normal"

Quite true regarding those stylists.  They know how to push my moto button!

[blackcat]

This is my point and was at the outset. 

I have experienced larger tires than those that came on Guzzis, SPs, EVs and others...  they just seem to steer in a truck-ish slow manner with tires that are larger than those they were designed for.

Even just putting a 120 rear vs a 110 on an 80's Tonti has made a difference.. to me.

Best,
Rob

I just changed back to the stock sizes on my CX as I didn't care for the larger sized tires for the same reason.  The Bridgestone Spitfires didn't help, as I hated those tires compared to the Sport Demons.  Just putting the bike on the center stand with the larger rear tire was a pain.

[Arizona Wayne]

I just changed back to the stock sizes on my CX as I didn't care for the larger sized tires for the same reason.  The Bridgestone Spitfires didn't help, as I hated those tires compared to the Sport Demons.  Just putting the bike on the center stand with the larger rear tire was a pain.

If you went from a 100/90 on the front to a 110/90, that was a mistake on a CX, unless you downsize the rim height too like I did, 18" to 16" like my `87 LM IV had.

On my LM IV going from a 120/80 front to a 110/90 front tire fixed it's sometimes head shake.    Trial & error is how I find out what works for me. 

[rodekyll]

I am amused when people argue their "opinions" against the actual facts.  It's particularly percious when an actual fact gets labeled opinion because the fact differs from an ignorant belief system.  This topic has been most entertaining in those respects.  Thanks to everyone who played.

So Dusty -- 'splain us the 18 wheeler in this context.  25 words or less.  Ready . . . . .  GO!

[oldbike54]

 Well , it has 18 wheels , therefore 18 tires , what else ya wanna know ?

 Dusty

[Huzo]

Well , it has 18 wheels , therefore 18 tires , what else ya wanna know ?

 Dusty

The one I drive in Australia has 34 wheels and it needs them all due to the 70 tons (max) trying to push it towards the earth's core! In the case of the bike, I'd be tempted to think that the tyre size requirement is also a function of the amount of torque it will be expected to transmit and the mass it supports, without destroying itself in the process. I wonder what would happen if you took a tyre off an early Le  Mans and cobbled it onto a Hyabusa? Traction might be ok, but it wouldn't survive the first few hard launches. Maybe the thicker walls that are required for modern powerful bikes, would mean a narrower tyre would not have the requisite flex required for a nice ride ??? 

[oldbike54]

The one I drive in Australia has 34 wheels and it needs them all due to the 70 tons (max) trying to push it towards the earth's core! In the case of the bike, I'd be tempted to think that the tyre size requirement is also a function of the amount of torque it will be expected to transmit and the mass it supports, without destroying itself in the process. I wonder what would happen if you took a tyre off an early Le  Mans and cobbled it onto a Hyabusa? Traction might be ok, but it wouldn't survive the first few hard launches. Maybe the thicker walls that are required for modern powerful bikes, would mean a narrower tyre would not have the requisite flex required for a nice ride ??? 

 If you took a tyre off of an old Lemans it would be really old 

 You are getting the concept Peter , the short sidewalls of modern street and race tires are much stiffer than the stuff we grew up with , but with modern suspension the tires don't need to flex , except modern radials are designed to flex . Confused yet ?

 Dusty

[Huzo]

If you took a tyre off of an old Lemans it would be really old 

 You are getting the concept Peter , the short sidewalls of modern street and race tires are much stiffer than the stuff we grew up with , but with modern suspension the tires don't need to flex , except modern radials are designed to flex . Confused yet ?

 Dusty

Was from the start. That's what I love about having a lousy ability to store facts, I get hear new and interesting things every 10 minutes !

[ssmith996]

I did notice that my Ducati 996 did turn faster with a 180 rear tire versus the stock 190.  After 2 180s, I did go back to buying 190s.  On the street, which is where all my riding is done, it just didn't matter.

[Arizona Wayne]

I did notice that my Ducati 996 did turn faster with a 180 rear tire versus the stock 190.  After 2 180s, I did go back to buying 190s.  On the street, which is where all my riding is done, it just didn't matter.

I rode a 996 once....it was so overpowered for the street I couldn't imagine using it for that.  1 time I met an older rider at  Sears Point raceway who had a Huyabusa.  Asked him how fast he'd had it up to.  He said never over 80 mph.    Said he used it for touring.

[ssmith996]

I rode a 996 once....it was so overpowered for the street I couldn't imagine using it for that.  1 time I met an older rider at  Sears Point raceway who had a Huyabusa.  Asked him how fast he'd had it up to.  He said never over 80 mph.    Said he used it for touring.

When I first bought my 996 back in 1999, I too thought it was overpowered for the street.  Then I bought my 2015 Ducati Monster 1200S last year......cured me of thinking the 996 was overpowered......