Topic: The Largest Tires I can get?

[JerryRice]

I own a 1974 CB350F. I want to get modern sport bike tires (tread pattern).
What is the fattest size I can go in the rear and front that will fit my rims?

Thanks!

[TwoTired]

What is the internal rim width for the tire bead on your rims?  1.85 inches or narrower?

Do you care if you get poor tire mileage and increasingly worse handling as they wear?  Are you going to put miles on the bike or mostly ogle it standing still?

[JerryRice]

I dont know the rim soze - hopeing someone knows since it is stock cb350F.

I will mostly ogle it standing still

Short cafe trips etc.

[ttr400]

Jerry,
I'm referring here to the CB400F, the CB350F uses the same size rims.
Front rim 1.65 x 18. Rear 1.85 x 18
The nearest metric equivalent tyres to use are front 90/90-18, Rear 100/90-18. I like the Avon AM26 tyres for my street 400's.
Many 400F guys also fit 100/90 front and 110/90 rear. I have ridden 400's with these sizes and the bike handles fine. Although I prefer the smaller sizes. The 100/90 on the front is a tight fit.
The rims are not wide enough to go any bigger. I did once have a 120 rear tyre on my 400 but it's just to big for the rim and made the turn in slower.

kevin

[JerryRice]

Thanks, I jjst saw a pic of the Avon AM26. HOT!

[JerryRice]

Would I use standard size tubes on the Avon AM26 ?

[ttr400]

Yes. Can't remember the size off hand, but ask when you get the tyres.

Kevin

[malcolmgb]

my 400f came with standard size wheels and unused but old Dunlop K825 tyres, front 90/90 rear 110/80. 90/90 is almost the same diameter as 3.00 so speedo is correct, the 110/80 is identical diameter, problem is the 'pinch angle' refered to on another posting is quite a lot greater than it should be so tyre shape is deformed on narrow rim.

[malcolmgb]

The nearest metric equivalent tyres to use are front 90/90-18, Rear 100/90-18. I like the Avon AM26 tyres for my street 400's.
Many 400F guys also fit 100/90 front and 110/90 rear.

The rears you mention are listed on the Avon site as universal tread, do you know how the pattern differs.

[RRRToolSolutions]

Jerry, tires and rims are made for each other for a reason - motorcycles turn and go around corners at speed because the tire's center is larger in circumference than it's edges. You don't turn a bike around corners like a car or trike - it's like a cone or dounce cap - when you put it on the table and roll it - the large end travels a lot farther then the small end. When you put a wide tire on a small rim - you are making that difference much more than the engineers and design people intended. You reduce the rubber contact patch that is responsible for traction in the first place, you increase the aspect ratio of side/center/side drastically and dangerously. The tire/rim marrige is one of safety, one of balance, one of getting the proper tire patch and turn - Trust me, if you just got to have more tire - lace a new rim made for the tire you want to run. The shape of the "U" will drastically effect handling, braking, and turn-in. It's a very bad idea.

No one says you shouldn't have your wide tires - just do it the right way, please. Lace a wider rim to the hub. It may look cool just having a wider tire, but you can get into serious trouble with turn-in and laying corners. It's not the smart thing to do.

Regards,
Gordon

[RRRToolSolutions]

I can't leave this alone -

I wish everyone would spend the $25 to get their own copy of the Motorcycle Safety Foundation's Guide to Motorcycling. This book has, does, and will save lives. You young guys need to read it - you have your families and futures ahead of you. You older guys need to read it to understand the math and statistics behind the science. This is my 2nd copy - the original and the advanced. Both are well written and I never pick up my copy and not pick-up something I missed or had forgotten from it.

Anyway, what you see below are 2 tires. The first is a BTX057 which has almost cost me serious injury more than once - it is pointed because it was made with a dual compound. The center is very hard rubber for long life and mileage while the sides are very soft, super-grippy rubber. Theseare both Z-rated 170 tires on the correct rim, but my point in all of this is that your tires need to be round, not pointed. I live in the mountains and during fast rides, the rubber on the sides of this 1st tire would get peeled away. This eventually (1,000 miles total) made this tire "pointed". When you turn the bars slightly to left to initiate the lean right - centrifical force pushes the bike over to it's right side. You quickly offset that with your handlebar to control the turn-in. With pointed tires (those curved way beyond design limits because you have too much tire on a narrow rim or like this first one who's sides are eaten away) - the bike immediately "over turns" - it wants to turn faster than your lean compensates you for. The effects are horrific, scary, and extremely dangerous. Not only have you created a pointed tire - you've lost valuable contact between the surface and your tire's patch. Two things very important when motorcycling.

Make any sense? I mean no harm, do be careful and don't worry about how it looks. Learn to ride that bike to it's limits with it's 3.50x18's and your friends won't say a word. I have a fried with one of those and at Deals Gap I could not catch him in the twisties with 60 horsepower more than he had. Those are sweet handlers and are not limited by their narrow tires.

Gordon

[kghost]

Good couple posts there brother

[crazypj]

In my opinion the vast majority of riders would be better off with slightly narrower tyres as they rarely, if ever, exceed 30 degree lean angle.
 Flatter profile would give greater stability when upright.
 for the real 'carvers' a slightly wider tyre allows bike to drop into corners quicker and at greater lean angles.
 In fact, you get more rubber on the road when leaning than you do when upright with slightly wider tyres ( only problem is, if you go too wide the sidewalls flex too much and tyre 'rolls' on rim)
 PJ

[JerryRice]

Awesome advice Ilbikes !

[goon 1492]

 Ibikes, in the midwest here everything is flat(Kansas more than Missouri), Ya'll livin' in texas know what I mean and alot of the tires I see are like the first pic. that is only because they don't get into the twistys much and just go straight on the highway hence the flat spot. That is a very good write up though brother.
I was also stating this because most of those riders that get that straight line flat spot don't realize the dangers of it like you said and they should get a saftey manual.

[ct_racer]

no kidding abut that flat spot.  I used to ride my buddy's cbr 600 and his tire was horrible.  It became a real inconvenience to have to "feel" for the tire to keep traction ridding on that narrow little bump.

[lordmoonpie]

I agree w/Gordon that if you push your bike you should not exceed the recommended tire width and profile for your rim.  That said, and as I do not push my 350 very hard, I'm running a 110/90 on the rear.  If I were more agressive I don't think I would go any fatter than a 100.  There is considerable clearance on the 350 and you could lace in a wider rim if you must.

Great advice Ilbikes *but* there is an assumption in there that the manufacturer got it right in the first place. When Kawasaki released the original ZZR1100 it had a 170 section rear tyre on it and most people replaced it for a 180 section as it made the bike noticeably more stable at speed. While this might be the exception, it proves that you shouldn't blindly accept what the manufacturer says you should use...