Sammy,

As you already know the indicated speed error increases when a Wing tire is installed on the front of the T. The error increase is about 3.9% or 2.5 mph at 65 mph. If overall your T is 5 mph fast at 65 mph then the speedometer error is also about 3.9%.

The 160/80-16 rear tire slows the engine speed down slightly by about 80 rpm at cruising speed. That is not a bad thing, but on the other hand it is not much different. The calculations are shown below.

The three other factors concerning whether you may a beneficial or detrimental switch to different tires are handling, load capacity and longevity. Regarding handling, although I have had limited experience with direct comparisons between bias-ply and radial tires, I have found the bias-ply tires from Dunlop and Michelin to be very good both on dry and wet roads. Others have reported no detectable difference in how well the bias-ply tires handle on a T compared to radial tires of the same size. There are differences when changing tire sizes no matter whether you are comparing one size bias-ply tire to another or one size radial tire to another or a bias-ply of one size to a radial tire of a different width and aspect ratio. Narrower tires turn faster and wider tires are more stable both in straight sections and as long as they are not too wide (like over 190mm wide) in the turns as well. Please note also that placing a narrower tire on the same wheel will flatten the profile of the tire. It would be good to check to see what wheel width the tire you mounted is recommended. Which model Dunlop did you install?

The T's OEM front and rear tires are rated for 660 lbs and 855 lbs respectively at the full rated tire pressure of 42 psi. The tires you installed are similar, 9% less in the front and 4% more in the rear. I have forgotten what the load capacity of a T is, but I expect with 420 to 430 lbs. of rider, passenger and luggage you are close to it. Overall, although the distribution is different you have a little more capacity (2.9%, 45 lbs.) and it is in the rear where it is needed with passenger and luggage.

Some have found that radial tires have more life than bias-ply and other have found the opposite. It depends on the hardness of the rubber of the applied tires. I guess you will find out which lasts longer and if that is acceptable to you. On my Nighthawk I just switched from a Michelin sport-touring bias-ply tire to an Avon sport-touring radial tire. I am in the process of finding out too. Good luck to both of us...

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Fred