Topic: So, help me understand this tire thing...

[Gonzowerke]

What am I gaining/losing if I went with a 100/90-19 front (stock size rim) and a 140/80-18 or 150/70-18 on a 3.5 inch rim in the rear.  I realize I may need to obtain a 77/78K swingarm to make this work as well.

Racing it is not my intentions but I like to play once in a while.

I wouldn't put a 150 on a 3.5 inch rim mate, tire is too big.... 140 is a better size.... Some tire manufacturers have a rim to tire size chart on their site, i would be looking at that ....

According to the PDF on this site that I mentioned earlier, a 140/80 is just fine on a 3.50 rim, while a 150/70 wants a 4.25 inch rim.

[Retro Rocket]

Go ahead! Or PM me, and I will try my best. I don't think you will be a thread killer.
Another thing to remember is, Front tires go on the front, rear tires go on the rear! I know, seems like a no brainer, but you'd be surprised!

This one will surprise you Gonzo. I owned a GPX750 [Ninja}superbike, it was raced very successfully here in Oz, it had a compK Metzeler rear 16 inch 130-16  tire run in reverse on the front, it handled brilliantly and i rode it like that for quite a while, there were piles of guys that ridiculed the set up but, while that bike was a production racer it was the only 750 in the top ten bikes in the last Castrol 6 hour endurance race, my mate Greg who raced the bike would have finished much further up the list if his co-rider wasn't 2 seconds a lap slower than him......So like everything else, whilst it isn't the normal thing to do there are exceptions....

[Really?]

I can dig that.  I was using this chart.  Maybe that chart is not the greatest. 

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cts=1331248416269&ved=0CE0QFjAA&url=http%3A%2F%2Fwww.mediafire.com%2F%3Fw7ke0q2t3dx7tz9&ei=RydZT7qyIKOLsgKR-Jm0DQ&usg=AFQjCNHWGBZYPCRqSRDPVWRunP6lPM99pA

[MCRider]

I've got two charts: dansmc.com and woodyswheelworks.com that say 150 is fine on a 3.5 rim, even 160.

[Retro Rocket]

I've got two charts: dansmc.com and woodyswheelworks.com that say 150 is fine on a 3.5 rim, even 160.

Sorry Ron but thats wrong mate, there are some poorly put together charts around, go to the tire manufacturers for advice.....A 160 on a 3.5 inch rim is plain stupid..... A 160 is a tight fit on a 4.25 inch rim....  profile makes a difference as well, as the side wall profile goes up, the tire will fit a slightly smaller width rim but there's no way i would be running a 150-160 tire on a 3.5 inch rim.....

[MCRider]

I've got two charts: dansmc.com and woodyswheelworks.com that say 150 is fine on a 3.5 rim, even 160.

Sorry Ron but thats wrong mate, there are some poorly put together charts around, go to the tire manufacturers for advice.....A 160 on a 3.5 inch rim is plain stupid..... A 160 is a tight fit on a 4.25 inch rim....  profile makes a difference as well, as the side wall profile goes up, the tire will fit a slightly smaller width rim but there's no way i would be running a 150-160 tire on a 3.5 inch rim.....

Could be, I personally don't know, granted.  But, I gave my sources, where's yours?

[Retro Rocket]

I've got two charts: dansmc.com and woodyswheelworks.com that say 150 is fine on a 3.5 rim, even 160.

Sorry Ron but thats wrong mate, there are some poorly put together charts around, go to the tire manufacturers for advice.....A 160 on a 3.5 inch rim is plain stupid..... A 160 is a tight fit on a 4.25 inch rim....  profile makes a difference as well, as the side wall profile goes up, the tire will fit a slightly smaller width rim but there's no way i would be running a 150-160 tire on a 3.5 inch rim.....

Could be, I personally don't know, granted.  But, I gave my sources, where's yours?

I didn't know this was a tit for tat thread Ron, mine comes from working in bike shops and working on bikes for over 30 years, i already said to ask the tire manufacturers for their recommendations, they know best.... If you read the rest of my posts in this thread you will see that there is a lot more involved than just sticking different size wheels and tires on, lots of things to consider if you want the bike to retain its handling characteristics.....

[MCRider]

You said I "was wrong" when all I did was offer an objective 3rd party opinion complete with backup. dansmc is a well respected mc site, woodys has been building wheels in Denver for near 40 years.  Why would i necessarily give you more cred over them?

I accept what you say as a valid opinion from your experience. You can't give me the same consideration?

tit for tat?

[ChuckG750f1]

This thread is very important to me since I need to replace the tires on my f1.  I don't want to hi-jack this conversation but...if I go with a 120/90-18 rear and 110/90-19 front (stock rims), am I ok?  Thanks.

[brooze72]

Ha! An "Oldtimer" tire thread!  I'm gettin out the popcorn now..

[MCRider]

This thread is very important to me since I need to replace the tires on my f1.  I don't want to hi-jack this conversation but...if I go with a 120/90-18 rear and 110/90-19 front (stock rims), am I ok?  Thanks.

IN MY OPINION, and based on the two tire charts i have, one says those sizes are OK and one says those sizes are too big for the rims (2.15 rr and 1.85fr)

I agree that the final arbiter should be the tire manufacturere you choose. Especially since you are pushing the threshhold generally.

[Retro Rocket]

You said I "was wrong" when all I did was offer an objective 3rd party opinion complete with backup. dansmc is a well respected mc site, woodys has been building wheels in Denver for near 40 years.  Why would i necessarily give you more cred over them?

I accept what you say as a valid opinion from your experience. You can't give me the same consideration?

tit for tat?

Settle down mate, i said "thats wrong" meaning the chart, i never said you were wrong because you didn't state anything from your own experience..... Believe what you want Ron, i have a 4.5 inch, 3.5 inch, 2.75 inch and 4 inch rims all with tires on right here mate and i am sure if you read the whole thread you will find the same advice from other posters about tire and rim sizes, 150 and 160 are far too wide for a 3.5 inch rim, you only have to see them side by side to work that out....

[Stev-o]

I, too, am shopping for tires for my K4. Am thinking about going with BT45's - 100/90-19 F and 120/80-18 R.  Is 20mm too much of a difference on the width?

Another thing about tires should be mentioned, age.  During a close tire inspection the other day, I noticed tiny dry rot cracks. Then I looked t the date of manufacture and they were made in 2001. I think 11 year old tires have run there life regardless of amount of tread, I started looking for new tires immediately.

[Retro Rocket]

I, too, am shopping for tires for my K4. Am thinking about going with BT45's - 100/90-19 F and 120/80-18 R.  Is 20mm too much of a difference on the width?

Another thing about tires should be mentioned, age.  During a close tire inspection the other day, I noticed tiny dry rot cracks. Then I looked t the date of manufacture and they were made in 2001. I think 11 year old tires have run there life regardless of amount of tread, I started looking for new tires immediately.

No 20mm isn't too much, on modern bikes the difference can be as much as 80MM or more. Most modern bikes use 120's on the front and the rear can go from 150 to 200 mm, all using the same sized front

[TS250]

Not to add more clutter here, but it was mentioned once at the top of the page, and seemingly ignored:  Tire profile, not just width, is important in selecting rim size.  The rim has to be matched to the appropriate width AND profile of tire.  I know most know this, but for those who don't...

[Retro Rocket]

Not to add more clutter here, but it was mentioned once at the top of the page, and seemingly ignored:  Tire profile, not just width, is important in selecting rim size.  The rim has to be matched to the appropriate width AND profile of tire.  I know most know this, but for those who don't...

+1  with higher profiles it is possible to fit slightly wider tires, the front profile will have changes to the rake and trail, same as rim sizes on the front.

[Really?]

I, too, am shopping for tires for my K4. Am thinking about going with BT45's - 100/90-19 F and 120/80-18 R.  Is 20mm too much of a difference on the width?

This thread has helped me a lot.  I am looking at the BT45's as well - 100/90-19 F and 140/80 or 70-18 on the back.  Need to decide which profile is better to match the front.  Looking at Buchannan's Sun rims also - 3.5-18 on the rear.  Both anodized black.

Thanks everyone for the discussion, I really appreciate it! 

[Stev-o]

Really - Rocky Mt ATV has the best prices on the BT45's I have seen and free shipping...


http://www.rockymountainatvmc.com/p/49/-/181/750/-/19426/Bridgestone-Battlax-BT45-V-Rated-Rear-Motorcycle-Tire

[754]

 I ran a 150/18 on a stock 750 rear rim...rode it to Bonneville and back.. kept up to my buddies CB 750 K8 in the twisties.. I donthing either of us corners very hard..I was running struts on the back of mine..
 Anyway, it seemed to work..

[Duke McDukiedook]

I think my next set for the 750 will be Dunlop K70 for the front and rear. They have the 3.50 X19 for the front and the 4.00 X 18 for the rear, just what Mark suggested. 

[Retro Rocket]

I ran a 150/18 on a stock 750 rear rim...rode it to Bonneville and back.. kept up to my buddies CB 750 K8 in the twisties.. I donthing either of us corners very hard..I was running struts on the back of mine..
 Anyway, it seemed to work..

That is a massive tire for the stock 18 Frank, i ran a 140 in the early 80's on a stock rim and it worked well but you could clearly see it was at the limit of what should be used on a stock rim, i can't remember the profile though, it was a Michelin.  I rode the wheels off that bike, it was an 810 kitted K6.