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

[palerider]

From what I recall, the contact patch size (total area) is not affected much, if at all, by the profile of the tire.
The shape of the patch will certainly vary, but the size of the patch is entirely dependent on the amount that the rounded tire deflects, which is more related to the weight of the machine and the pressure in the tire. When a lower profile allows a wider patch, the weight being supported by a wider area of tire will deflect the tire less producing a shorter patch. And vice versa.

Now the shape of the tire might bias the various performance characteristics of the tire differently; for instance, the lateral adhesion (for cornering) vs. longitudinal traction for acceleration and braking. Just something else to consider.

Good point. Also the patch will vary between tires of the same size but from different manufacturers and even from the same manufacturer within different models of the same size. The PR4s contact patch will be different from the PR3 and so on. Every tire is going to have slightly different ride characteristics.

As sentient humans, we get to make choices. We listen to advice, weigh that advice, then decide for ourselves what is best for us. My 1984 V65 Magna was supposed to have bias ply tires on its cast wheels. Radial tires for motorcycles were not widely available in 1984, so naturally enough Honda never considered them that year. Years later, some gutsy member of the Magna forum had the courage to try a radial. It fit, and it transformed that bike, making it handle and ride 100% better. Did it have a different contact patch than the officially recommended bias ply? Uh huh. Would Honda and Allstate have approved? Certainly not. Might it have caused problems with insurance payouts? Maybe. Who knows? It would have been a battle of experts. My experts would have said the radials, even if not officially approved, actually made the bike safer. A jury would have decided.

But as someone who tries to be in control of my own life, I chose to run radials on the Magna. That's what freedom and liberty is all about. That's why I ride motorcycles. What's sad is the number of people who are so scared of the world that they abdicate their individual sovereinty over their lives and allow paragraphs in magazines to dictate their choices.

 

[CA G-Man]

palerider:

While I agree with you almost 100% as indicated by my earlier posts in this thread, I don't know that anyone is allowing "paragraphs in magazines to dictate their choices." I think that those paragraphs in magazines are just one of the sources of advice that you reference; some people may put more weight on those paragraphs in their calculations than they do other sources of information and advice. As you point out, that's their choice to make.

So with that said... is this horse dead yet?

 

[palerider]

palerider:
While I agree with you almost 100% as indicated by my earlier posts in this thread, I don't know that anyone is allowing "paragraphs in magazines to dictate their choices." I think that those paragraphs in magazines are just one of the sources of advice that you reference; some people may put more weight on those paragraphs in their calculations than they do other sources of information and advice. As you point out, that's their choice to make.

So with that said... is this horse dead yet?

Apparently not.

 

[RaYzerman19]

OK, I'm going to throw out a very flawed theory that there MAY be a smidgen of truth to the different profile theory...... last year, I mounted a 190 Metzeler Z8 on the rear..... chosen because I prefer a slightly softer compound for grip, and curious about the Z8 in general. It was a hot day in July where you could fry eggs on the pavement. Running 44 psi, two up, tire about 1500 miles old. Earlier in the afternoon, I THOUGHT I felt the rear losing a teeny bit of grip during some aggressive cornering (not scraping pegs but leaned over pretty good). Later in the afternoon, on a well travelled street where there is a lot of commuter traffic during the week, I came up to this tight curve which I know fairly well, and went into it aggressively, again not scraping pegs but close. Speed, maybe 40 mph. The rear definitely stepped out to the point of becoming a pucker moment requiring correction. Again, the pavement was very hot, and I told myself that one reason could be there was invisible rubber residue on the road from all the traffic scrubbing off rubber as they go around this corner (it had not rained for at least a week to wash it off), compounded by the extreme heat.................. dunno, lots one can theorize about. Just a very flawed data point requiring further testing this year.

Edit 01-04-2016 - New theory. Wore out the Z8 and installed PR4. PR4 is defnitely more planted than the Z8. Z8 is a little too soft perhaps..... done with them. PR4 working great, feels very planted, my new favourite rear tire. No issues in aggressive cornering, good in the wet.

 

[user 8909]

2k miles and I'm still alive with my set of T30's and the 190 on the back.

I experienced a down pour on the interstate one day and these tires felt much more secure than the previous Avons. Tar snakes were another issue but I suspect the squirminess would be felt with any tire.

As far as the size goes I felt the same as everyone else has and will continue to enjoy them.

 

[csi]

Guess I shouldn't mention that I haven't balanced an m/c tire in close to 100,000 miles.

Remove the wheel weights, and toss in 4 ounces of Dyna beads......

 

[HyperPete]

Guess I shouldn't mention that I haven't balanced an m/c tire in close to 100,000 miles.
Remove the wheel weights, and toss in 4 ounces of Dyna beads......

I agree on balancing beads, but I've been using these for years instead of Dyna beads. $1.70 / ounce.

https://checkeredflagtirebalancebeads.com/

 

[BobCo]

I spent too much of my time going through this topic yesterday. I hope that this info from Avon will put to rest whether 190/55ZR17 tires are okay on 5.50" width rims. At least it's okay with these tires.

 

[HotRodZilla]

BobCo...I'm glad that's ok, because my last three sets if tires have been 190/55/17. None have popped off yet. Haha...Good find.

 

[DennisJ]

FYI, now I'll sit back and watch the cats quarrel!

Thanks, copied and saved. This will come in useful sometimes.