Upsizing Rear Tire to 190/55 (w/ pics)

[Top_Speed1]

As Howie says; Darksiding see's even bigger footprints. I guess us fatsiders are just taking baby steps

Nah...y'all are just a bunch of man-whores who won't commit to a TRUE relationship.

HS, these are my g/f's Debbies words EXACTLY! .....hey, I just think you should share the love!

Always DID wonder what happened to you after your television career....

You became a bouncer at a titty bar???

Close enough!

 

[FJRat]

Ho hum...benn running 190/55 ever since I got the FJR. Been flamed about the slower turn in [not noticeable,run a couple pounds more pressure]..As mentioned-rpm's are lower, mileage higher, looks better....All manufacturers list a 5.5 inch rim as acceptable fitment for a 190. A 200 is interesting but the tire is designed for a 6 inch rim and may be pinched so much that there would be no width gain. Hope someone tries it and posts up. Could always send the wheel out to Kosman and have it widened-we could maybe run a 240 [and it wouldn't be square..] Fat bottomed girls make the world go 'round..

Does anyone know for sure what is the widest rim the FJR can take?

I would hate to send my wheel to Kosman, make it 6 rim and not be able to fit a 200, maybe not even a 190...

BTW: it appears to me that if one wants to gain 'contact' patch, a 190 would actually have less contact on a 5.5 rim than the 180...and the sensation of the bike dropping into the turns more quickly may come from the squeezed pin-ball concave shape prompted by the 5.5 rim pinching the 190. But I would guess, going around the turns with a 190 you also have less contact. Someone unconvincingly argued this point with me before on another forum. I would have to see evidence to change what appears to me the logical physics of a 190 on 5.5 rim versus the OEM size.

rational disagreements are welcome, save your flames for your barbecue.

 

[lnewlf]

Seems to be plenty of room for the rim-it's the tire that might interfere..might have to move the torque link out [darkside boys would know about that]..

can't scientifically speak to the size of the contact patch..it might actually be larger due to the steeper angle of the "pinched" 190..Chicken strips will be larger. Some pure sport bikes use a 190 on a 5.5 rim..

 

[CA G-Man]

I just picked up my bike with a new T30 190/55 on it last night. After 12 pages there's been lots of discussion in this thread about the effects of the change from 180 so I'll just add my initial first-hand observations.

I've only got 13 km on the new tire (a short ride home from the shop) so I can't speak to the performance aspect (turn-in, etc.), except that I suspect some of the earlier observations about needing less pressure to hold a turn may be accurate. That could be more the result of the "new tires" effect, but time will tell.

On an eyeball assessment, the 190 mounted doesn’t look any wider than the old 180 off the rim and lined up behind the 190. As others have noted, with the 190 it is easier to get up on the centre stand – and I was surprised at how much of a difference it made. There is almost exactly a half-inch of air under the tire when on the stand.

As for the contact patch, my only observation is that the profile of the 190 at the edge looks very steep; so much so that I can guarantee I will always have significant chicken strips and, for anybody riding this tire who thinks they won’t, I can pretty much guarantee you’ll be scraping a lot of hard parts before eliminating the chicken strips, regardless of what suspension you’re running. I’m not sure what the effect of this steep edge profile will be on the size/stickiness of the contact patch when cornering, but again, I guess time will tell.

I didn't have my GPS on for the ride home so I can't comment on any speedometer error correction, but I think the only question is how much it will be corrected.

 

[RadioHowie]

Does anyone know for sure what is the widest rim the FJR can take?I would hate to send my wheel to Kosman, make it 6 rim and not be able to fit a 200, maybe not even a 190...

It's already been mentioned once in this thread, but it apparently has been ignored, so it bears repeating...

There's NO need to consider widening the rim of the FJR to accommodate a 200 tire. It's 5.5 inches and a 205 fits like a glove without ANY rim kludging.

However, the brake torque arm required modification.

 

[Top_Speed1]

I just finished a 4 day ride with "Wine Guy" (and a large bunch of others). He was one of the latest to pop on a 190/55 (he went w PR2) at "wnyfjr" tech day on 6/7. Nothing but praise is all I heard. Now granted, it's nothing as extreme as what Howie is talking about in CT/Darkside world.

 

[RaYzerman19]

My darkside was worn out and I put on a 190/55 for the time being. I must say the turn-in was much faster than I expected or remember OEM size rears to be... after a little adjustment I was kinda liking it a lot. It has 2000+ miles on it now, and I'll only offer an opinion, that whatever initial difference there is between a 190 and 180 is likely to be somewhat worn off or maybe more accurately, worn in, after a couple of thousand..... it still turns in very well and I doubt the contact patch is any different than a 180. The chicken strip sizes are normal, same as a 180, and I don't see any compromise in having a 190 that would concern me. I like grippy tires, and I do have confidence in the 190....... I'm not a fan of the harder PR2's that some like (or perhaps the PR4), again, I like to know my tire is a bit grippier..... mine is a Metzeler Z8. I'll give a PR3 a shot next time if I don't go darkside again. I may do a 'what the heck' trial of the PR4 who knows....

 

[FJRat]

My darkside was worn out and I put on a 190/55 for the time being. I must say the turn-in was much faster than I expected or remember OEM size rears to be... after a little adjustment I was kinda liking it a lot. It has 2000+ miles on it now, and I'll only offer an opinion, that whatever initial difference there is between a 190 and 180 is likely to be somewhat worn off or maybe more accurately, worn in, after a couple of thousand..... it still turns in very well and I doubt the contact patch is any different than a 180. The chicken strip sizes are normal, same as a 180, and I don't see any compromise in having a 190 that would concern me. I like grippy tires, and I do have confidence in the 190....... I'm not a fan of the harder PR2's that some like (or perhaps the PR4), again, I like to know my tire is a bit grippier..... mine is a Metzeler Z8. I'll give a PR3 a shot next time if I don't go darkside again. I may do a 'what the heck' trial of the PR4 who knows....

I hope you or no one else take offense to this...just my thoughts

I don't see how a 190/55 can have a bigger nor equal footprint than a 180/55 on the same size rim. The reason why the 190/55 improve transition is because you are riding on a smaller strip of tire which make the vector force to turn lower, plus, the bike sits a hair higher in the back which narrows the turning radius. This is the consequence of squeezing a wider tire on the same size rim.

If you were to put a 220 on a wider rim on the FJR what you would experience is the exact opposite, a larger patch and more force required to push into a turn

Someone with racing experience may pitch in here to comment of the parameter of efficacy for a motto tire going around a curve. I suspect that is the target of the engineer who design these bike.

I lowered my bike which ruins maneuverability but improves stability on the straight away hwy ride. Since I am not a twisties freakoid I opt for the characteristics of a more straight away stability over nimble maneuverability.

...tis what the car tire does...you trade one thing for the other...

 

[garyahouse]

My darkside was worn out and I put on a 190/55 for the time being. I must say the turn-in was much faster than I expected or remember OEM size rears to be... after a little adjustment I was kinda liking it a lot. It has 2000+ miles on it now, and I'll only offer an opinion, that whatever initial difference there is between a 190 and 180 is likely to be somewhat worn off or maybe more accurately, worn in, after a couple of thousand..... it still turns in very well and I doubt the contact patch is any different than a 180. The chicken strip sizes are normal, same as a 180, and I don't see any compromise in having a 190 that would concern me. I like grippy tires, and I do have confidence in the 190....... I'm not a fan of the harder PR2's that some like (or perhaps the PR4), again, I like to know my tire is a bit grippier..... mine is a Metzeler Z8. I'll give a PR3 a shot next time if I don't go darkside again. I may do a 'what the heck' trial of the PR4 who knows....

I hope you or no one else take offense to this...just my thoughts...

...tis what the car tire does...you trade one thing for the other...

But the CT gives you SO much more of the one thing...

I was wondering: just how wide can ya go with a rear tire?

Gary

darksider #44

 

[RaYzerman19]

My darkside was worn out and I put on a 190/55 for the time being. I must say the turn-in was much faster than I expected or remember OEM size rears to be... after a little adjustment I was kinda liking it a lot. It has 2000+ miles on it now, and I'll only offer an opinion, that whatever initial difference there is between a 190 and 180 is likely to be somewhat worn off or maybe more accurately, worn in, after a couple of thousand..... it still turns in very well and I doubt the contact patch is any different than a 180. The chicken strip sizes are normal, same as a 180, and I don't see any compromise in having a 190 that would concern me. I like grippy tires, and I do have confidence in the 190....... I'm not a fan of the harder PR2's that some like (or perhaps the PR4), again, I like to know my tire is a bit grippier..... mine is a Metzeler Z8. I'll give a PR3 a shot next time if I don't go darkside again. I may do a 'what the heck' trial of the PR4 who knows....

I hope you or no one else take offense to this...just my thoughts

I don't see how a 190/55 can have a bigger nor equal footprint than a 180/55 on the same size rim. The reason why the 190/55 improve transition is because you are riding on a smaller strip of tire which make the vector force to turn lower, plus, the bike sits a hair higher in the back which narrows the turning radius. This is the consequence of squeezing a wider tire on the same size rim.

If you were to put a 220 on a wider rim on the FJR what you would experience is the exact opposite, a larger patch and more force required to push into a turn

Someone with racing experience may pitch in here to comment of the parameter of efficacy for a motto tire going around a curve. I suspect that is the target of the engineer who design these bike.

I lowered my bike which ruins maneuverability but improves stability on the straight away hwy ride. Since I am not a twisties freakoid I opt for the characteristics of a more straight away stability over nimble maneuverability.

...tis what the car tire does...you trade one thing for the other...

No offense taken. You're possibly right about the profile differences when brand new. I speculated that it will change as the tire wears in, and will conform more to the normal 180 profile. Remember too, that a 190 is only 5 mm wider on each side than a 180, and that ain't a lot of difference. Only saying that doesn't worry me a bit, and especially after I gave it a good workout in 2000 miles.

 

[SunRider]

About to order up my second 190/55.

Prefer its turn-in feel.

Easy-up centerstand a bonus.

 

[sparky99]

sorry for the resurrection. just a quick question, would the increased rolling diameter mess with the traction control on a genIII ?

 

[Uncle Hud]

Yes. Expect bike to burst into flame from overloaded TCS circuit.

Actually, that's a good question. If the larger rear tire rotates slower (even 1% slower) than the front .... I suppose the TCS has a "blind spot" if the difference in rotational speed is very small, but that's an assumption.

What would the TCS response be? Constant application of front brakes? That might be funny to watch.

Try it and let us know. Video, please.

 

[lnewlf]

you just opened the proverbial can of worms for those DrkSdr dudes

 

[ionbeam]

What happens when the OEM tire is at the lower limit of inflation? What happens when a replacement tire is within RIM diameter, section width and aspect ratio spec but none the less is a slightly different diameter than OEM?

Howze about the ECU looks for a change in the wheel speed ratio between the front and rear wheels instead of an absolute wheel speed measurement difference? As soon as you roll away the ECU can calculate the wheel ratio. If you pull away with the rear wheel spinning the ratio will be wildly off, so with no other ratio value stored the ECU still knows something is wrong. I suspect that if the ECU saw the front/rear wheel ratio was constantly outside a window of acceptance by a small amount it would pop an error code and warning light. Typically, the ECU would correct a wheel speed ratio issue by managing power to the rear wheel via FI mapping and spark mapping, taking away power until the wheel ratio is back in specification or hits a low limit value.

 

[Fred W]

Meh... not such a big can of worms.

It does say explicitly in the manual that you must use the correct size tire for the TCS to function correctly. And yes, there is no doubt that there is some amount of tolerance in the allowable wheel diameter. Consider this, the front wheel is always turning a little faster than the rear due to the smaller circumference of 120/70-17 vs 180/55-17. The sidewall height on the 120/70 front should be about 84mm, and the rear 180/55 will be about 99mm. So there already has to be an allowance built in to the firmware to tolerate different wheel speeds.

Rear wheel spin would be detected by it increasing rotation speed faster than the front. Putting a larger size tire will cause the wheel to turn slower than normal, so that will not cause the TCS to think it is spinning.

When it does detect wheel spin it changes ignition timing, throttle opening (via Fly By Wire) and fuel injection cut. TCS doesn't do anything with the brakes. If it believes the rotation speeds are out of range, like when you do a wheelie or rotate the rear wheel on he center stand, it just disables the TCS and turns the TCS light on.

 

[Uncle Hud]

(Yeah, brakes are ABS-controlled, not TCS-controlled.)

 

[Top_Speed1]

I'm still amazed that ole Ray-Ray took off his CT and mounted up a 190/55 MC tire (or any MC tire for that matter). I always thought, once a DSer, always a DSer. ???

 

[Denver_FJR]

... Consider this, the front wheel is always turning a little faster than the rear due to the smaller circumference of 120/70-17 vs 180/55-17. The sidewall height on the 120/70 front should be about 84mm, and the rear 180/55 will be about 99mm. So there already has to be an allowance built in to the firmware to tolerate different wheel speeds....

No doubt there is some allowance for different wheel speeds due to turning, tire variance, etc, but the ECU only knows pulses/second it gets from each ABS sensor ring. I'd be curious to know if the two rings have different number of elements, thus normalizing the number of pulses received between front and rear.

 

[ionbeam]

...I'd be curious to know if the two rings have different number of elements, thus normalizing the number of pulses received between front and rear.

In all probability the pulse wheels have the same number of elements because it determines the resolution of the readings. There is no real need to normalize the pulses because the ECU is real good at math