Tire ride height

[MN72Busa]

Well got a new set of Michelin Pilot powers, & after reading the December issue of sport rider I have a few questions about overall tire height.

<span style='color:red'>Michelin front 120/70/17 - Circum: 1894
Michelin rear 190/50/17 - Circum: 1972</span>

I dont know the stock Bridgestone specs so I will use the BT-014 for comparison as I figgure this is close to what the stock tires are on my busa right now.

<span style='color:red'>Bridgestone front 120/70/17 - Circum: 1886
Bridgestone rear 190/50/17 - Circum: 1975</span>

<span style='color:blue'>The Michelins seem to be: 8 mm taller up front
The Michelins seem to be: 3 mm shorter in the rear</span>

Is this considered a big difference? Also lets take into account that I believe the stock rear tire that came on the busa was a 55 series and the new Michelin is a 50 series.

Sport Rider's comment on the Michelin's "The tall front tire, combined with somewhat short rear tire on both bikes, required the front ends on both bikes to be dropped by more than a few mm".

Does this mean I should lower my front end, either by lowering tripple trees, or another method to obtain neutral or optimal ride characteristics? Will there be a noticeable difference due to ride height? Any pro's or con's to the ride height of the Michelin's over the stock Bridgeston's ride height?

 

[jwcfbd]

The fit between the front tire and fender is very close. I would stick with the tire size that came on the bike. Trust me it's not fun when the tire rubs the inside of the fender. I had the wrong tire installed on my Busa. It was to tall and the wrong speed rateing. I over sped the tire and it tried to rub through the fender. In my case the wrong speed rateing may have been the problem but I wouldn't chance it.

 

[Charlesbusa]

I don't have the article with me, but it looks like you quoted their circumference number, which would not be the tire's height. I think they called it section height.

Stock busa tire is a 50 aspect ration on the rear not 55.

Don't forget tires grow when they get hot. Just to add to the confusion.

 

[MN72Busa]

Michelin front section height : 70mm
Michelin rear section height: 82mm

Michelin front sidewall height : 25mm
Michelin rear sidewall height: 28mm

Are you saying the Pilot Powers will rub? I thought this is what everyone was using around here?

 

[Charlesbusa]

If you keep with the stock numbers

120/70zr17
190/50zr17

You won't have any rub.

Did they list any bt-56 section heights?



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[MN72Busa]

no they didnt - also went on the bridgestone website, looked up the BT56, and they didnt list the section heights for front or rear.

 

[Charlesbusa]

Its a diffcult question to find an answer to.

Maybe someone will know...

 

[Turbo-Torch]

You're talking about mm's circumference which will equate to...oh...about a the thickness of a strand of your hair in height. Measure 10 of the same tires from the same manufacturer and I'll bet each one will vary +/- 8mm in circumference.

 

[Tufbusa]

Unless you are an exceptional rider, change tire brands and you'll never know the difference. However, any suspension guy will tell you not to change tire brands once your bike is set up unless you reset your suspension afterwards. All the tire manufacturers make their tires the same height and diameter from one tire to another. Example, you can go from your OEM Bridgestone BT56 to their BT14 and you will find both will be the exact same size in diameter and circumference. Same with Michelin or Dunlop etc. Your busa came with Bridgestone tires, if you change brands of tires it will also change the handling characteristics of your bike. If you are an average rider, you'll probably never notice the difference. If you are a top ten racer, you'll notice the difference instantly.

For the average guy on the street, I don't think it matters much which tire you install. I'd say buy whatever tire you like and ride it as hard as you can. There is probably not one guy out of every hundred, maybe less, that can ride any quality sport tire to it's maximum potential.

My favorite tire is the BT14. It's a bridgestone so I don't have to reset my suspension when I leave my stock 56's behind. The 14 is an outstanding street tire as well. Dual compound with great handling at any speed and exceptional grip on the outside portions of the tread. It doesn't have the agressive race profile of the pilot power which, in my opinion, makes it a better everyday street tire. The price is right which makes it even more appealing.

 

[Churchkey]

8MM difference in curcumference will not be noticable by anyone even the best track  rider.

8MM is .320 inch or for you tape measure guys a hair over 5/16 of an inch. You can change the circumference of a tire that much with air pressure.

Circumference also refered to "roll out" by racers is the distance a tire will travel in one full revolution.

The comparison figure you need to work with is tire diameter, the overall height of the tire. If you only have the circumference measurement to work from find the diameter by converting the MM measurement to inches & dividing that  measurement by Pi (3.1416).

Your 1894 MM figure will be 75.76 inch circumference.

TIre diameter is then 24.115 inch

Your 1886 measurement is 24.013 diameter.

The difference is .102 inch in diameter.

Since fender clearance is an issue you need to cut that figure in half as only 1/2 of the tire is above the axle center line.

The tire with the larger circumference will be .051 closer to the fender. Thats less than 1/16 inch.

EDIT: The true ride height will be effected by the .051 figure however the side wall construction of different brands of tires will effect the "squat radius" of the tire. Squat radius is the amount the tire compresses at the contact patch under load. Its the distance between the rim & the road. The new tire may or may not deflect as much as the old tire while under load. Changing air pressure effects squat radius.

My main concern when purchasing tires is like sizes & traction. I like soft tires that are sticky & have good wet weather characteristics.

Good luck



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[MN72Busa]

8MM difference in curcumference will not be noticable by anyone even the best track rider.

8MM is .320 inch or for you tape measure guys a hair over 5/16 of an inch. You can change the circumference of a tire that much with air pressure.

Circumference also refered to "roll out" by racers is the distance a tire will travel in one full revolution.

The comparison figure you need to work with is tire diameter, the overall height of the tire. If you only have the circumference measurement to work from find the diameter by converting the MM measurement to inches & dividing that measurement by Pi (3.1416).

Your 1894 MM figure will be 75.76 inch circumference.

TIre diameter is then 24.115 inch

Your 1886 measurement is 24.013 diameter.

The difference is .102 inch in diameter.

Since fender clearance is an issue you need to cut that figure in half as only 1/2 of the tire is above the axle center line.

The tire with the larger circumference will be .051 closer to the fender. Thats less than 1/16 inch.

EDIT: The true ride height will be effected by the .051 figure however the side wall construction of different brands of tires will effect the "squat radius" of the tire. Squat radius is the amount the tire compresses at the contact patch under load. Its the distance between the rim & the road. The new tire may or may not deflect as much as the old tire while under load. Changing air pressure effects squat radius.

My main concern when purchasing tires is like sizes & traction. I like soft tires that are sticky & have good wet weather characteristics.

Good luck

Thanks for the conversions...some great input. I guess after reading SportRiders blurb about lowering the front becuase of the tire height, It made me wonder. I also like sticky tires and tires good for the rain as I ride in quite abit of rain...Im hoping the new Pilot Powers do the trick for me....I went on the input of the board members here talking about them positively.