Inside The Numbers====TIRES

[AirportFF]

Well after a lengthy discussion with a guy at a dealership (not the typical crook) today. I have finally figured out the numbers on tires. Since we are in the good old USA, I prefer inches over millimeters.
While researching info for the upcoming CBR swap on Susan's bike. I wanted to get a tire that was close to the same overall diameter as the stock tire. But the stock wheel is a 15" and the CBR is a 17" So after much scratching of the head and almost burning out my calculator I have some info.

The stock rear tire on the SS 750 is a 160/80-15

The 160 represents the width in millimeters
The 80 means that the sidewall is 80% of the width
The 15 is the rim size

So, if you take the 160 and multiply it by .80 that will give you the sidewall height in mm's. Then take that number and multiply it by .03937 to convert it to inches. Take that result and multply it by 2 (sidewall on top and bottom of tire) and ten add the diameter of the rim, in this case 15"
This will give a pretty close overall measurement of the entire wheel.

Let's review: 160 x .80=128mm
128 x .03937=5.03 inches
5.03 x 2=10.07 inches
10.07 + 15=25.07 inches total height

So now I want a wider tire that will fit on the CBR 17" rim and still be near the stock overall diameter. What I found was a 200/50-17. The overall diameter of this will end up being approx. 24.87" which is just under the stock tire diameter.

The front tire is a whole different challenge. The stock front is 19" and the CBR is 17" I need to find a tire that will fit the smaller rim but have a taller sidewall that won't leave a huge gap between the tire and fender.

The stock front is a 110/80-19 with an overall diameter of 25.92 inches

The closest I've found in total diameter is a 120/90-17 which has an overall diameter of 25.5 inches. But the problem with this is that the tire is 10mm wider and that presents a clearance issue to the fender mounts. So the next available size would be a 110/90-17 which has a diameter of 24.79" which would make the gap between the fender and tire a half inch wider. That I can live with.

Just for quick reference these are the inch equivalants for rear tire widths

210mm=8.2677"
200mm=7.874"
190=7.4803"
180=7.0866"
170mm=6.6929"
160mm=6.2992"

owwww....my head hurts :eek7:

[Corpsegrinder]

Nice work there professor!!

[AirportFF]

After all of this I'm now wondering if the 200 will fit under the fender with the subframe.
And the only 110/90-17 for the front is actually a rear tire. So I'll probably end up going with the 110/80-17 in the front and move the fender mounts down. Unless anyone has a 120 in the front and it clears the fender mounts. INPUT???

Anyone that has a 200 Metz on the back with the socks and sub frame in place let me know how it's working out. Pics would help.

[RustyJake]

I've got a 200 on the back. My rim is a 5.5" wide 18" rim. The tire is a 200/50-18 with a subframe. Took some altering but it's there. There is NOT a lot of clearance on the chain side, but it does clear. I've got 11-1/2" progressive shocks on the back too.
You didn't have to type all that out.........it's right here: http://www.cruiseconcepts.biz/sizedoesmatter.htm
A thing to consider when choosing your tires is choosing a relationship that will be the same. Both my front and back tires are larger diameter then what the stock tires were. My speedo is actually MORE accurate now then it was with the stock tire. My front is now a 110/90-19

[AirportFF]

You didn't have to type all that out.........it's right here: http://www.cruiseconcepts.biz/sizedoesmatter.htm


Sure bud, rain on my parade
What can I say, I was bored

I can't find a 110/90-17 that's for the front. The only one I've found so far is for the rear. The CBR rim is 17x3.5 in the front. I'm worried that if I go with a 120 in the front I won't have enough clerance on the sides for the fender mount. I might just go with a 110/80-17 and live with the wider gap that will be left between the tire and fender.

I think in the back I'll just go with the 190/50 or 55-17. There's no big difference but anything to give a little more clearance.....

[RustyJake]

I had an email from someone at Metzeler and their recommendation was 1/4" clearance on the sides and 1/2" clearance on the top.
They would err on the side of caution and give you more then enough clearance with their recommendations. On my chain side I have just a bit over 3/16" clearance between the tire and where the bolt is in the subframe (it's ground down as well to give more clearance) . You are gaining less than 1/4" in the difference between the 200 and 190 in widths on each side. It may make it so you don't have to alter as much, but I'm sure you'll still have to do some modding under there. It also makes a big difference in the width of the rim as we discussed before in another thread.
When I set out to keep my subframe, I didn't find too many people that tried to keep theirs. Nor did I find much information on keeping it. It's not that big of an alteration, I don't think you'd have any difficulty with it at all.

[AirportFF]

The rear is 17 x 5.5" and Susan isn't carrying any passengers and is a hell of a lot lighter than me. I'll wait till they get back from the polisher and worry about it then

[RustyJake]

I'll help where I can if you decide to go that route. I'll take pictures and measurements of whatever you need. Just let me know.

[AirportFF]

I know you'd help. I just like figuring it out on my own. You know that if I ask a question that I'm stuck.... :wink_2:

[ickmak]

I have a 210 and I had to take out my subframe The sides of the tire is almost hitting the fender.

[Tiger-Ray]

I've got a 200 on the back. My rim is a 5.5" wide 18" rim. The tire is a 200/50-18 with a subframe. Took some altering but it's there. There is NOT a lot of clearance on the chain side, but it does clear. I've got 11-1/2" progressive shocks on the back too.
You didn't have to type all that out.........it's right here: http://www.cruiseconcepts.biz/sizedoesmatter.htm
A thing to consider when choosing your tires is choosing a relationship that will be the same. Both my front and back tires are larger diameter then what the stock tires were. My speedo is actually MORE accurate now then it was with the stock tire. My front is now a 110/90-19

Rifle,

Thanks for the link. So I need an 200/50/18 rear tire to fit on a 5.5" rim. Do you have a link to the rim I need that I can purchase?...wife said least expensive if possible. Has to be easy. Wife wants to buy it for me for a present.

Thanks

[RustyJake]

Width of rim doesn't dictate the overall size of the tire. Usually a wider tire will require a wider rim to seat properly.
200 is the width in mm, 50 is the cross section, so in this case the cross section (veiwing it like a donut) is 100 mm (50% of the width is sidewall). 18 is the ID of the rim (in this case 18", which my rim is)
I don't know what cheap is to you, that's a relative term and in most cases it's going to cost a bit to get a wider wheel in the back unless you stick with the stock rim.

[Feesgida]

Has anyone ever used a wider tyre on the stock front. I am getting the setup for the vtx mod but was wondering if someone ever did something with the front

[750SpiritRdr]

Tire Diameter Calculation ( Just for information )
Most people will want to know a tire diameter (measured in inches). This formula is a quick way to get the tire diameter of those metric tires that are common on just about everything stock. For example a 200/55R18 would be around 26.7 inches tall and 7.9 (200mm/25.4) inches wide. Enter any three of the numbers into this formula to solve for the fourth. "R" means Radial and "B" means Bias tire. The bigger number (on the left) is the Section Width in millimeters (1"=25.4mm). The number to the right of the slash ("/") is the Aspect Ratio (percent of width). The "R" means Radial tire and the last number, far right, is the rim diameter in inches.

Tire Diameter = Rim Diameter + (2 x Aspect Ratio x Section Width) / 25.4


Example (200/55R18 tire): Tire Diameter = 18 + (2 x 0.55 x 200) / 25.4 = 26.7 in

IF THIS DOSEN'T EXPLAIN IT THEN ASK BEAKER, HE'll BE HAPPY TO EXPLAIN IT TO YOU.

[shawnbtrouble]

I searched different tire threads till my eyes bled, :rolleyes3 please forgive the asking if it's been asked before...
Needing a new front tire, very unhappy with the stock Dunlop the bike had, not quite as, but still unhappy with the lowpro Bridgestone I have on now, very interested in the Metzeler 110/90-19 I read so much about in the threads... I unfortunately still have a Dunlop on the rear with a lot of miles left on it, must have gotten one of the 4 goods ones made that year...I did not notice any negative riding issues from having the Bridgestone/Dunlop combo. Now the question... Will running the Metzeler front-Dunlop rear result in any negative handling/riding issues??? :freak:

[JayT]

They "say" You must match tires due to the added compounds in the tires, If you have a tire on the rear thats not as soft or hard as the front, you risk the rear hooking up and the front sliding out or visa versa
But then you look at all the custom frame bikes like big dog, fat daddy, pro street and so on, and they all use different rears....

IMO if your an all weather renegade then match, but if your out in dry weather only just stay close to matching.

[Canyonrunner]

Try this link: http://www.discounttire.com/dtcs/infoTireMath.dos

Of course the speedometer change indicated only applies to front tires when calculating motorcycle tire sizes.

[shawnbtrouble]

:brood: They "say" You must match tires due to the added compounds in the tires, If you have a tire on the rear thats not as soft or hard as the front, you risk the rear hooking up and the front sliding out or visa versa
But then you look at all the custom frame bikes like big dog, fat daddy, pro street and so on, and they all use different rears....

IMO if your an all weather renegade then match, but if your out in dry weather only just stay close to matching.

Yeah I've read so many "they says"... I ride as much as possible, rain, cold, heat. I have not braved heading out in snow and ice, although I have been caught in a snow a couple of times and rode through a hail storm once. >OUCH<:stars: I also ride like crazy on 2 lane twisted treasures as often as possible... Too dang confusing, one says if their both bias, it wont matter, one says if its different names it matters, one says... ARGH!!!!:furious2: I will be heading to the Dragon/Cherohala area in October, I really want to have good, SAFE, skins under me... The rear Dunlop has just too much life left to swap them both, guess I can get a matching front and just save to swap both soon...:uneasy:

[feellnfroggy600vlx]

Just get a read to match the frnt you want and sell the old rear, someone out there neds a rear tire bad.