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Rear tire upgrade

Started by Shane4371, December 28, 2015, 03:52:50 PM

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Shane4371

Stock 86 fj1200,what's the widest tire I can run,anyone tried a 160 or 170?

rktmanfj

Randy T
Indy

Blessed be the LORD my strength, which teacheth my hands to war, and my fingers to fight.
Psalms 144:1

'89 FJ1200
'90 FJ1200
'78 XT500
'88 XT350


Shane4371

I think the 150 tire looks to narrow,wider will help the look for me,so avon 160,is availible?

FJmonkey

Quote from: Shane4371 on December 28, 2015, 04:34:01 PM
I think the 150 tire looks to narrow,wider will help the look for me,so avon 160,is availible?

Shane, it may look better but FJ riders with 150 wide tires can ride faster than FJs with 180 wide tires, it is the rider, not the tire. This might also help you understand why tire width and rim width either work together, or against.

http://www.sportrider.com/does-size-matter
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

Shane4371

I got the Avon Am26 160/80/16,like the wide look.thanks tho,Is a 130/ 80/16 a good match.I hope so cause I'm vested now

FJmonkey

Quote from: Shane4371 on December 28, 2015, 07:36:04 PM
I got the Avon Am26 160/80/16,like the wide look.thanks tho,Is a 130/ 80/16 a good match.I hope so cause I'm vested now

For the front, the 120 is already pinched on the 3" wheel. Go gently in the twisties now that you are vested...
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

rktmanfj

Quote from: Shane4371 on December 28, 2015, 07:36:04 PM
I got the Avon Am26 160/80/16,like the wide look.thanks tho,Is a 130/ 80/16 a good match.I hope so cause I'm vested now

Well, as long as it looks good... 
Randy T
Indy

Blessed be the LORD my strength, which teacheth my hands to war, and my fingers to fight.
Psalms 144:1

'89 FJ1200
'90 FJ1200
'78 XT500
'88 XT350


Fred R

To know what width your tyre on your wheel might be , use this.
Width of wheel in inches x 25.4+30   +/_ 10
With the stock wheel this Will be
4.5x 25. 4+30 =144.3   +/_ 10 so can be minimum 135 and maximum 155

Arnie

FredR,
That's an interesting formula, but to quote a phrase I learned back when I took my first programming class, in 1967, "GIGO"
In case you missed that acronym translation, it stands for Garbage In, Garbage Out. :-)
In this particular case, the OEM stock rear wheel is 3.5 inches wide, not 4.5 in.
So, plugging the correct rim size into your formula you get 118.9 +/- 10 giving you a 110-130 width tire.
That formula may have been a good general guide back when tires were 100 or 90 aspect ratio, but it just doesn't apply now.  Go by the tire or bike maker's recommendation (or maybe vary by one size)
Arnie

Quote from: Fred R on December 29, 2015, 01:03:32 AM
To know what width your tyre on your wheel might be , use this.
Width of wheel in inches x 25.4+30   +/_ 10
With the stock wheel this Will be
4.5x 25. 4+30 =144.3   +/_ 10 so can be minimum 135 and maximum 155

Shane4371

I dont see going one step wider is a issue.I don't drag my knees around corners. I like the extra tire to pavement.just wanted to know if going one step wider would cause any issues.thanks for the input

simi_ed

Shane, I think you got this upside-down. If you want more rubber on the road, go with a 140.  Narrower tire will be opened up more than a 160, putting more rubber down.  FYI, I run a 5" wheel with a 170/60x17 tire.  Plenty of rubber down there, until I go to a 5.5" wheel & 180 tire. 

Ed
-- RKBA Regards,

Ed
===
Ed Thiele 
Simi Valley, CA -- I no longer have SoCal manners.
'89 FJ12C (Theft deterrent Silver/White)


- All that is necessary for the forces of evil to win in the world is for
enough good men to do nothing.

- Edmund Burke

Fred R

Quote from: Arnie on December 29, 2015, 07:29:15 AM
FredR,
That's an interesting formula, but to quote a phrase I learned back when I took my first programming class, in 1967, "GIGO"
In case you missed that acronym translation, it stands for Garbage In, Garbage Out. :-)
In this particular case, the OEM stock rear wheel is 3.5 inches wide, not 4.5 in.
So, plugging the correct rim size into your formula you get 118.9 +/- 10 giving you a 110-130 width tire.
That formula may have been a good general guide back when tires were 100 or 90 aspect ratio, but it just doesn't apply now.  Go by the tire or bike maker's recommendation (or maybe vary by one size)
Arnie

Quote from: Fred R on December 29, 2015, 01:03:32 AM
To know what width your tyre on your wheel might be , use this.
Width of wheel in inches x 25.4+30   +/_ 10
With the stock wheel this Will be
4.5x 25. 4+30 =144.3   +/_ 10 so can be minimum 135 and maximum 155

You are right there, the fj wheel is indeed very small
ive used this with every 17 inch wheel in the past and there it ads up
for if the tyres are to wide they will act like some sort of balloon and will not act rigid

ribbert

There is of course a far less scientific and far more conclusive method than all these charts and theories....seat of the pants!

According to many, I run "pinched" oversize tyres on my bike. 180/5" on the back and 120/3" on the front.

This theoretically gives me less rubber on the road, tyre I can't use and heavy/slow steering.

I have RPM suspension F&R and the back raised.

The bike is now taller in the corners, and as a consequence, leans over further making the contact point higher on the fairing and other things, as evidenced by the photo below (It used to scrape towards the bottom of that flat section).



Even at these angles, but most of the time a bit less than that, I can hit the throttle.

Tyres only have one job, to maintain grip with the road, how much more grip do you need?

As for steering, the change in geometry makes it light turning in and even changing line mid corner effortless, it is nearer to the BMW than it is to a stock FJ.

The downside to "too big" tyres? None that I can see.
The downside to smaller tyres? None I know of.
Am I likely to outride the tyres on my FJ anyway? Not if you have reasonable to good tyres.
Am I going to crash because I didn't follow the fitment chart exactly? No.
Will my bike handle like a rubber cow because I went one size up? No.
Are there lots of members running bigger tyres without issue? Yes.
Are there lots of members running smaller tyres without issue? yes.
Does it really matter? No.
Why am I the only one silly enough to write about it? I don't know, where's "Empirical Man" when you need him?

Noel
"Tell a wise man something he doesn't know and he'll thank you, tell a fool something he doesn't know and he'll abuse you"

Urban_Legend

I like you thinking Noel. Does it really matter as long as you're comfortable with what you have under you.
Mark
Mark
My Baby (Sparkles)
84 FJ1100/1200 motor
92 FJ 1200 - Project bike. Finished and sold.
84 FJ1100 - Project bike.

Shane4371

Friends like how the bike has came along, but everyone is. Commenting on the skinny rear tire.I agree its skinny I cruise mostly.plus ride with my wife.their has to be a upside to wider.