Tire size and handling

[leighd42]

Okay cafe experts out there I have a '77 that had a Bridgestone Spitfire's 110/90-19 on the front and a 120/90-18 on the rear. It handled like crap being that it didn't want to lean into corners. I have kept the stock rim size for my build and purchased some Avon Roadriders 90/90-19 front and 120/90-18 rear. I was under the impression that a thinner front tire would greatly improve the handling but looking at the tire today it looks so skinny. Will this combo work or should I think about reducing the difference of 30mm between front and back to 20mm like stock sizes? I wanted a 100/90-19 front but it was special order so I went with the sizes in stock.

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[5twins]

I think these ride and handle best with 100 fronts and 110 rears. Those were the stock sizes or the nearest metric equivalent anyway. I'd say your problem is the 120 rear - it's too fat. Mine came with a 120 rear installed. I used it up then went to the more correct 110. What a difference. Although the 110 front probably isn't helping things either. Everybody wants to put fat tires on these bikes, why, I don't know. Probably for the "look". If that's what you want, learn to live with the crap handling.

 

[jayel]

make sure your fork bearings and swing arm bushing are up to snuff, also suspension, fork springs/rear shocks are good

 

[jd750ace]

Everybody wants to put fat tires on these bikes, why, I don't know. Probably for the "look". If that's what you want, learn to live with the crap handling.

+1 LOOK be damned! Bikes are for riding, not looking at!

 

[tonyc]

Jayel that is where I would look for handling first along with fork springs and shocks. Then I would go for good handling and proper size tires. I have have been riding Brit Bikes for years and it seems everyone wants fatter tires, yet the BSA'S, Norton, and Triumphs handle beter with the original size tires. By the way they are near the same size as our XS's.

 

[leighd42]

so will the 90 front and a 110 rear work? Or should I try and take both back and re-order 100 front and 110 rear? I have upgraded the rear shocks and new progressive front springs all new bearings seals etc etc in everything. I am thinking the biggest problem was the 110 front but maybe I am wrong.

 

[leighd42]

Okay guys looks like I can return the tires so what combo should I go for on this cafe build?

90/90-19 & 110/90-18

or

100/90-19 & 110/90-18

or

100/90-19 & 120/90-18

Thanks for the advice.

Dave

 

[tonyc]

100/90 19 tront
110/90 18 rear
This would be for standard model.

 

[leighd42]

Thanks TonyC

 

[jayel]

fork brace might help too

 

[5twins]

Oh, it will help big time. These bikes need one bad. When you grab that single front brake, the forks twist up like a pretzel, lol. I could see it happening on mine just sitting in the driveway and pumping the forks with the brake applied.

 

[Jack]

so will the 90 front and a 110 rear work? Or should I try and take both back and re-order 100 front and 110 rear? I have upgraded the rear shocks and new progressive front springs all new bearings seals etc etc in everything. I am thinking the biggest problem was the 110 front but maybe I am wrong.

The 90 up front will steer quicker than the 100 on a 19" rim

 

[Marlin72xs]

Only 4 years late, but here's my 2 cents. If you have ever shopped for tires on the DEnnis Kirk site, you may have noticed that for most of the tires he will show the inflated width and height. After searching for the perfect tire I realized that many if not all manufacturers heights and widths are different for the same labeled sizes.
For instance, a 120/80-18 might be 26.6 inches tall and another may be 25.8 inches. That's 3/4" smaller or 3/8" lower. 3/8" is not much, but it will change the steering geometry slightly, i.e., slower handling.
OK, poo poo, BFD, add a 110/90-19 front tire that might be taller than stock, and now the slow handling is even slower.
I emailed Avon about mixing and matching tires and they of course said don't, and they recommended the 3.25-19 front and a 4.00-18 rear. I bought the AM26, Roadriders. They handled turns great and they were quick and agile. The only thing I didn't like was the wobbling on rain grooves.
The moral of the story is, determine the inflated heights if at all possible and try to maintain the stock dimensions if you want the handling to remain the same.
I now use an Avon av54 Trailrider, 120/80-18. It's also 26.6" tall and 4-5/8" wide. I wanted a 60/40 tire for N. GA for grassy fields and dirt roads. I have no problems with it on the road.

 

[Marlin72xs]

I hate when people write novels.

 

[Max Midnight]

Try telling that to J K Rowling......

 

[Marlin72xs]

I was talking about myself, Max. And yes, maybe not all together, but my body is falling apart too.

 

[Tomterrific]

100\90\19 front, 110\90\18 back. Just like everyone says. The 90\90\19 will be quicker turning but may look too small.

If I write too little it seems I'm misunderstood. I attempt to hit all the bases.

Tom

 

[TimeMachine]

Two more cents, After riding an FJ1200 very fast for a few years, I took to liking a heavy planted front end. Now my XS' s are not considered or ridden as sport bikes by me. I still prefer some extra rubber up front because I occasionally ride two up and just like the heavy feel. Fits my riding style and country road selection. So see , we all have to match our bikes to our riding habits. Take this as a positive please... RT

 

[jetmechmarty]

I put a 90/90-19 Avon on the front of my Special for some time. It fit fine and turned in quick. It had plenty of contact patch for an XS650. If your primary concern is filling up the front fender, this tire is not for you.

 

[YAM277]

Getting the right size being the most important, does anyone have feedback on the Firestone Coker's?
On a second note, it still cracks me up, when someone says Para Moose instead of Par Ram Us! Marlin Understands!