Tires to get

The 550s rear rim may be smaller/narrower than the 650's.
Since the stock Rr tire is 3.75-18, I'd guess the 110/90 would be the appropriate size, but the Rr tire in your photo is a 120/90. I don't know much about tires.

The motorcycle tire mfg websites should spit out the correct size when you use their cross-reference.
I tried the Dunlopmotorcycle.com site, but the 550A isn't listed. However, the site lists the 110/90-18 for the 550 GPz - its Rr rim (2.15x18) is probably about the same as yours, but I really don't know what sizes are suitable for your rims..

martin_csr wrote: The 550s rear rim may be smaller/narrower than the 650's.
Since the stock Rr tire is 3.75-18, I'd guess the 110/90 would be the appropriate size.
The motorcycle tire mfg websites should spit out the correct size when you use their cross-reference.
I tried the Dunlopmotorcycle.com site, but the 550A isn't listed. However, the site lists the 110/90-18 for the 550 GPz - its Rr rim (2.15x18) is probably about the same as yours.

Spot on Martin, there 18x2.15. I checked with a distributor and they mentioned I had the correct conversions.

Is there anything you don't know about these bike's Martin?!

I have a workshop on 1/8/14 to install these new tires. I'll post pictures when they're on.

I hit reply too soon. doh. & added some disclaimers. hee.

PS: I dont' know that much & have been wrong on more than a few occasions... the steel ball for the clutch for instance. doh.

0Z.Z1R Mk2 wrote: My favorite tires for old kwaka's are the "Pirelli Sports Demons".

Running Pirelli's front and rear on my old KZ.

TheDude wrote: I will look into the "Demons".
Are they long-lasting? I'm not aware of how long tires last for on motorcycles.
.

Here is what my KZ-750 does: For typical tires: you are lucky to get 7k out of a rear, a really premium rear tire might go 10k. Front tires usually last a very long time and get replaced when the sidewall starts to dry rot.

TheDude wrote:

650ed wrote: On my KZ650-C1 I use 100/90 V -19 on the front, and 120/90 V-18 on the rear and they work great. Ed

Is the KZ650-C1 different from the KZ550-A3?

I feel more comfortable getting the front-100/90-19 and rear-110/90-18, but if you guys says the 120 is fine for the rear, then why not.

I also run 100/90-19 on front and 110/90-18 on rear. Next size up (120) MIGHT fit on my rear, but 110 looks closest to original which was 4.00-18.

I ran 130/90 v 18 tires on the rear of my KZ650 for many years, but they didn't perform any better than the 120 tires because the cross-section of the 130 tires were deformed by squeezing them onto the narrow rim. The 120 tires fit the rim well with no distortion of the tire. I won't be going back to the 130 tires (man were they hard to mount on the rim!). I suspect the 120 would work fine on the KZ750 twin if you ever want to try them, but I recommend you measure the clearance between the 110 tire and the frame, chain, etc. first to ensure there is enough space for the 120 (there should be). The only clearance issue I had with the 130 was the stock chain guard. The120 has no clearance problem at all on the KZ650. Ed

I think I will try the 120 next time mainly to up the gear ratio a tiny bit. I'm pretty sure it will fit. back in the old days of English sizes, I remember going up from the stock 4.00-18 to 4.60-18 and they fit in the fork.

After viewing the photos at home, I have just one thing to suggest. DO NOT ride that bike more than around the block on those tires. The mold date appears to be week 11 of 1980 in your first pic. Not sure how that is possible on a 1982 bike. Sincerely, if those tires are that old they will be like hockey pucks on fresh Zamboni ice. They are not safe to ride on. Any recently manufactured tire will be a huge improvement over those aged bricks. Good luck with your freshening up project. AND, when you can post some pictures of your bike for all of us to see.

Forrest wrote: After viewing the photos at home, I have just one thing to suggest. DO NOT ride that bike more than around the block on those tires. The mold date appears to be week 11 of 1980 in your first pic. Not sure how that is possible on a 1982 bike. Sincerely, if those tires are that old they will be like hockey pucks on fresh Zamboni ice. They are not safe to ride on. Any recently manufactured tire will be a huge improvement over those aged bricks. Good luck with your freshening up project. AND, when you can post some pictures of your bike for all of us to see.

Where do you see the mold date? Is it where it has the numbers 40-11-80?

Forrest wrote: After viewing the photos at home, I have just one thing to suggest. DO NOT ride that bike more than around the block on those tires. The mold date appears to be week 11 of 1980 in your first pic. Not sure how that is possible on a 1982 bike.

I guess because some places sell old tires that have been sitting on the shelf for a while.....

+1 on "retiring" (LOL) that rubber! I REALLY like my Avon roadriders! One happy side effect I experienced was the difference in the profiles between the old cracked tires I replaced, and the avon's. the difference manifested itself during turns....MUCH more gradual lean on the new ones! on the old ones, it felt like they had flat sides when I rolled up on them in a turn...(you could almost feel a "click") now I just keep leaning, smooth as silk! I haven't scraped a peg yet, but it's good to have goals in life!