Downsizing tires

Im thinking of going with 70 hight instead of 90 on my 83 kz650

Bad idea? Thanks

I doubt you will find such a tire suitable for a stock rim. Ed

Ive actually found several, thats why im asking, the reason i would go with a 70 is pure esthetics anyways, abviousy if the performance isnt decreased

What size / brand / model tires are they? Ed

its more than asthetics involved the first numeber ie:100 is the width in millimeters the second numbers is the aspect ratio Ie: 90 which means the side wall is 90% of a 100 millimeters or 90 millimeters convert that to inches add the rim size and tat gives you overall wheel diameter/ height
over all height will affect ride& speedometer
if you go smaller aspect ration and larger width you can keep overall diameter close
1" = 25.4mm 100/90/18 = over all heght 21.5" tall
100/70/18 = 20.75" tall 3/4 of an inch isn't much and its a mile depending on application
125/70/18 = 21.4 hight 70 aspect ratio is the 1/10 of an inch shorter in that respresentation
if you gp wider 140/70 then your side wall is actually taller than the 100/90 for a shorter aspect ratio you need to enlarge the rim diameter for the lower profile asthetics
hope explained that correctly

ramtough_63 wrote: its more than asthetics involved the first numeber ie:100 is the width in millimeters the second numbers is the aspect ratio Ie: 90 which means the side wall is 90% of a 100 millimeters or 90 millimeters convert that to inches add the rim size and tat gives you overall wheel diameter/ height
over all height will affect ride& speedometer
if you go smaller aspect ration and larger width you can keep overall diameter close
1" = 25.4mm 100/90/18 = over all heght 21.5" tall
100/70/18 = 20.75" tall 3/4 of an inch isn't much and its a mile depending on application
125/70/18 = 21.4 hight 70 aspect ratio is the 1/10 of an inch shorter in that respresentation
if you gp wider 140/70 then your side wall is actually taller than the 100/90 for a shorter aspect ratio you need to enlarge the rim diameter for the lower profile asthetics
hope explained that correctly

I know exactly how the tire hight system works im keeping the original width and just taking aaway from the height

as far as the tires themselves check out this link, there are several by avon, michellin and other brands

www.bikebandit.com/front-120-70-19-stree...294966520-4294966933

Thanks for the link. You stated that you are keeping the original width? Maybe I missed something, but I don't see any 70 profile tires that are even close to the original width or that will work well with the stock rims.

For the front I see 120/70-19 radial tires, but none narrower. The stock front tire width is 3.25". The normal metric size front tire is 100/90-19, and that is about 1/2" wider than stock. A 120 width tire is 4.5" wide; that's a huge 1.25" wider than stock! Trying to squeeze a wide 120 onto a 1.85 rim isn't going to work, especially with so little sidewall (70 series is low) to work with. If you somehow shoehorned that tire onto the rim the cross-section profile would be very distorted and would give unpredictable (but not in a good way) handling characteristics. Even worse, a tire that wide will very likely rub on the fender bracket.

For the rear i see 130/70-18 bias and radial tires, but none narrower. The stock rear tire is 4" wide. The 130 width tire in a normal profile (90) is 5". I can assure you from personal experience that mounting a 130 width tire with a 90 profile is challenging and distorts the tire's cross-section profile. I ran that size tires for years until I woke up and realized that a 120 width tire made more sense and handles as well or better. The 130 width tire in a low profile (70) is 5.10". Trying to fit a 130/70 rear tire on a 2.15 stock rim may prove impossible because on the short sidewall. However, if you were able to get it on the rim the tire's cross-section will be very distorted because of the short sidewall and that will impact handling. Ed

Current tires on the bike as ead off the sidewall are 110,90r19 front tubeless, 130,90r16 tubeless rear, both are shinko brand

So your bike is a CSR. The 130/90-16 rear tire is the stock size, but I do not see any 130/70-16 rear tires being offered. Did I miss something?

The 110/90-19 you have on the front of your bike is already 3/4" oversized for the rim, and frankly it's not helping your bike's handling. Going to a 120 will bump it up another 1/2". That's 4.5" instead of the stock 3.25". Way too wide for a stock 1.85 front rim in my opinion. Ed

It was just an idea to give the bike a lowered look

I honestly dont even know how the bike rides with the original since ive never riden it, right now the motor and carbs are rebuilt and its torn down to the frame, gona start cutting it this weekend then off to powdercoating, the only real issue ill have is relocating the stock pegs and shifter as that is for sure an uncomfortable possition, gona have to find a suitable replacement

Forget radial tires on your bike, it's not worth the hassle.
And if you know exactly how the tire measurement system works, then you're aware that those are just general numbers and no two tires from different manufacturers of the same specified size will actual be the same measurements?

Back in teh day, when I was racing my Corvair in SCCA Solo, I would go to the tire store with a tape measure in my pocket. Sometimes I'd have to measure 30 tires just to find four that were reasonably comparable in height. Same manufacturer, same model tire.

FORM FOLLOWS FUNCTION!!

If you change the size of your tires (larger or smaller) for aesthetic reasons, you're a poser. How do I come to this conclusion? I did it myself! I went one size up front and rear, thought my bike handled okay... then I went back to the proper size, and WOW what a difference!