tires diameter and rake

Skelton Hogs

Member
Riding for 9 Years
Local time
Today, 03:06
Apr 11, 2019
6
2
42
North York, Ontario
My Ride
2013 Rocket Touring
RE Tires
Ahoy! I haven't been able to figure this out and any experienced help would be great. Re 2013 rocket touring (both front/rear 16") Back tire is larger diameter and higher than the front. That is the rear tire sidewall (180-70-16) is 5% higher than the front (150-80-16) since "many" not all but many motos have larger (overall) front wheels for easier maneuvering, could this be the reason the rocket is tricky to turn because it has a smaller front tire? I realize the culprit is also the fat 150 front tire as well. Would the rake be forward leaning as well? Should I have 2 tires with the same overall diameter? The manufacture has their set up and reasons but I can't understand it. The chart below shows the O.E.M. set up. Any thoughts to changing to what the #2 chart below shows with Rear being 180-65-16 // Front 130-90-16 (same load ratings of course) The REASON why I'd like to change size is because the turning at slower speeds is challenging for me even coming off a Road king, Vmax, and other large cruisers, Thx in advance

Chart #1

150/80-16180/70-16Difference
Diameter inches (mm)25.45 (646.4)25.92 (658.4)0.47 (12) 1.9%
Width inches (mm)5.91 (150)7.09 (180)1.18 (30) 20%
Circum. inches (mm)79.95 (2030.73)81.43 (2068.42)1.48 (37.7) 1.9%
Sidewall Height inches (mm)4.72 (120)4.96 (126)0.24 (6) 5%
Revolutions per mile (km)792.5 (492.43)778.05 (483.46)-14.44 (-8.98) -1.8%


Chart #2 - Same overall diameter and sidewall height.

130/90-16180/65-16Difference
Diameter inches (mm)25.21 (640.4)25.21 (640.4)0 (0) 0%
Width inches (mm)5.12 (130)7.09 (180)1.97 (50) 38.5%
Circum. inches (mm)79.21 (2011.88)79.21 (2011.88)0 (0) 0%
Sidewall Height inches (mm)4.61 (117)4.61 (117)0 (0) 0%
Revolutions per mile (km)799.92 (497.05)799.92 (497.05)0 (0) 0%
 

Qship

Smile, you're on camera. Somewhere.
Riding for 38 Years
Staff
Local time
Today, 04:06
Feb 25, 2014
2,581
227
Near Fredericton, New Brunswick.
First Name
Steve
My Ride
'17 Tiger Explorer XRT
If the R3 is like my bike, the magnetic pick up on the rear wheel is used for the speedometer. Changing the profile on the rear tire will affect that and make it more inaccurate. Most bikes are at least 5% conservative on their speedo readings. Making the rear tire smaller and thus increasing revolutions per mile is going the throw that out further.
Making your tires the same rolling diameter is not going to change your low speed handling that you seem to dislike about your bike. Smaller diameter tires actually turn in quicker at highway speeds due to less gyroscopic effect. That's why sport bikes have smaller rims/tire combos than cruisers and off road type bikes typically have.
Tire makes and compounds dictate rolling resistance, tire life and handling characteristics. If the current tires on your bike are of a soft nature then they will be harder to maneuver at low speeds but provide better grip, but also wear faster.
Taller, narrower tires will help with your low speed maneuvering, but once you have changed the size, chances are you will have changed brand/make of tire, so you won't know what changes were brought about by the new tires(brand vs. width).
I believe HD cruisers mainly use Dunlop tires and they are typically a bit narrower and harder than the R3 meats, so if you wanted to try those in the stock size or slightly narrower width, it may improve the low speed maneuvering you seek but sacrifice some grip.
All I can suggest(if you haven't done it already) is research as much as possible online about tire brands, longevity, grip, etc to see which ones may help you achieve your goals
Unless you're rich and famous, the tires you buy will be around for at least 8-10K kms, so better make sure you'll be happy with them.
Hope this helps.
 
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triumph david

Riding for 59 Years
Staff
Local time
Today, 02:06
Nov 25, 2013
4,856
303
71
brookhaven
First Name
david
My Ride
1976 t140 Triumph, 2006 Road King, 1982 Honda CB 900 C, 1973 Yamaha 360 Enduro, 1972 Corbin
I think Qship said it all, i have ridden HD's and Triumphs all my life and i can say heavy bikes are in a world of there own. I like Triumphs because they are lightweight (some of them anyway) and handle great, and i like HD because they are heavy and have a solid feeling.