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putting a bigger rear tire on an 86 VT1100C

9K views 19 replies 9 participants last post by  guntarssuitins 
#1 ·
Hello,
Apparently, my 86 VT1100C has a 140/90-15 size rear tire. I think it looks a bit small for this bike. Could I put a larger one on without negatively effecting the handling? What size?
 
#2 · (Edited)
#3 · (Edited)
How much clearance do you have between the tire and swingarm?
'87+ came with a 170/80/15. Just not sure how different the swingarm is on them '85-86 compared to later ones.

The 170/80 is ~3/4 inch taller and is 1 1/4 inches wider. So a minimum of 3/4 inch clearance on each side of the tire with the stock size to even think of the 170/80.
A 160/80/15 is just a touch taller and ~3/4 inch wider, so would give you a little wider that stock, but not quite as much as a 170/80.

This is the site I use to compare tires, gives you a quick estimate the size comparison.
 
#8 · (Edited)
150/90/15 fits just fine on my 85 VT1100C. The 140/90/15 is the correct stock size. It is recommended to only go up one size to properly fit the rim width. Going any larger will affect the road 'contact patch'. Unless you only want it for looks instead of proper handling, stick to one size up rule.
 
#17 ·
DanMitch, I'm curious what brand of tire you went with for the rear? My 85' VT1100C has the original Dunlop 140/90-15 tire on it, which measures 5.45" width, leaving me 5/16" (0.2625") clearance between the tire and the drive shaft on the left. A new Dunlop Qualifier K-525 V-max tire is 6.26" wide - a difference of + 0.81", or + 0.405" on each side. Based on this, the new Dunlop would put me + 0.1425" over. Talk about splitting hairs - however, the new Dunlop K525 tires are Qualifiers with raised white letters, very closely matching the original tires, and I'd love to be able to use them. Any input ?? Thanks, JRL in Washington State
 
#9 ·
A 150/90 only makes the dia./O.D. .710 larger thus making the final output even taller than stock. There's no such one size up rule. Messing with the front tire size will effect handling more than anything. The OP needs to physically lower arse down and check his clearance on both sides and go from there.
 
#13 ·
It is true, h13man, there actually isn't a written in stone rule. It is common knowledge. Tire manufacturers state the minimum and maximum specs for tire size to rim size according to widths. Check the width of the rim and then the maximum width the tire manufacturer recommends to put on that rim. I believe you will find one size up in general.
 
#10 ·
I checked for clearance. Width is the problem area not diameter. There is only about 3/8 of an inch to the side between the stock tire and shaft housing on the swing arm. So it appears that the 150/90-15 would be the largest size that I could fit. Unless I could find a 160/90-15(but a quick internet search did not show anything).
 
#11 · (Edited)
I'd say 160/80 be the max. but that's 20mm O.A./10mm per side. Last I checked 3/8" is smaller than 10mm. A 160/90 doesn't exist. 150/80 would be a choice but Shinko & Metzler are the only brands available from http://www.americanmototire.com/catalog/. 140/90 seems to have the most variety. I wouldn't go any taller/larger O.D. or might find your self using the clutch more than normal from a stop.


https://www.tacomaworld.com/tirecalc?tires=140-90r15-160-80r15


https://www.tacomaworld.com/tirecalc?tires=140-90r15-150-80r15











>:) :wink2:
 
#12 · (Edited)
160/80/15 is the same width as 160/90/15.

As I said before, the 160/80/15 is only 4mm taller than stock, so no real change in that, and it is 20 mm wider, so 10 mm on each side, which is just above your limit for shaft clearance (you say "about 3/8" clearance, which is 9.5mm).

Motorcycle tires will have a slightly different profile that the charts since those are for car tires, so you may or may not have the clearance you need, only way to know for sure is to get a tire and try it. Problem is, one manufactures 160/80/15 could be just a little wider or narrower than another manufacturer, so it is hit and miss unfortunately.

edit:Looks like H13man beat me to most of it.
 
#14 ·
So I was practicing/testing my brakes and couldn't help but notice what a wide streak my back tire left on the road. I'd have to measure it to be sure, but it seamed about 3" wide which just looks really wide compared to how small the back tire looks on the bike. That's when I noticed the shape of the 140/90-15. The tire seams to have a shape which allows for maximum surface area to road as compared to the 150/90-15 which is much more rounded and has a smaller strip that makes surface contact. This would probably be an issue for drag racing, but I doubt that it would have an effect on much else.
 
#15 ·
how many burnouts has the 140 done? My dad would buy new tires every year because he got them for damn near free. From time to time he would get a brand that he just didnt like the shape of so he would "reshape" it by doing a massive burnout and then leaning the bike from side to side. Did a great job of grinding the grown down but he didnt care about longevity in the slightest.
 
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