Fat Tire questions...

[yoothgeye]

To me, a tire just can't be fat enough, eityher on my MTB, BMX, or Rat.

Here's my question, won't my tire appear to be fatter if I mount it on a narrow rim?

Seems to me that this would buldge out the sidewalls, thus making your contact patch smaller, but appearing to be a bigger tire than if mounted onto a wider rim.

Am I correct in this?

 

[badmuller]

Interesting question.
At first I thought a wider rim would make a tire look huge.

after trying it i'm not so sure, i have a fatfrank on a 3cm wide rim for one bike

and a electra diamond tread(same size as f.f.) on 5.5 cm wide rim

to me it doesn't seem to make a lot of difference.

i've seen tires on the rigida rims that can be up to 10 cm wide, and that looks fat.
i would like to see them start making a series of rigida rims that are wide and have a more classiclook.

 

[icyuod2]

maybe these pictures will help.
you can't see the rear rim, but let me assure you, that's about the skinniest your gonna get.
not because they don't make em skinnier, but with the oversized tire and narrow rim, i had to manipulate the beads of the tire and valve stem into place (it was a very tight fit) any smaller and i wouldn't have got them in.

the front rim is considerably wider. do ya notice much of a difference?

here's another of mine with real skinny rims, again it was a real tight fit for both beads and valve stem.

those narrow rims also make the tire smaller, mine measure about 2 3/4" across.

 

[Unchained]

Hmmm, interesting thought. I think it's a visual illusion of sorts, because looking at both wide and narrow rims I could go either way. It would make sense that a narrow-er rim would add beef to the tire, even just visually, because of the stark contrast. On icyuod2's bike above, that's exactly what happens to me when I see it, the tires make the rims look extra thin, and vice versa :mrgreen: As far as actual sidewall bulge and contact surface changes, it makes sense, but I don't know how you could ever prove it or test it. Take the same tire and tube to a wide and less wide rim, and measuring around them, rim edge to rim edge, at the same pressure? For contact sufrace, I think you could ride through a puddle and onto dry pavement with both setups... :mrgreen: Just a guess. Could be a lot of fussing for not much difference.

 

[yoothgeye]

Thanks guys... the bike I recently built has the same size tires, but different sized (slightly) rims, I will see about getting some measurements/photos to see if my theory holds any water. It's not about changing the actual size of the tire, but how it appears.

I'm basing this on my knowledge of tires on my 4x4, I had the same 31x10.50-15 tires mounted on a set of 10" rims and 7" rims, the 7" rims made them look bigger (more sidewall buldge), the 10" rims made them look smaller. Then I mounted the exact 31" spare on a 4.5" rim, it looked really fat from the side, but skinny from the front.

 

[Rustinkerer]

I think it depends on the tire design. I have kenda ww's on my late model Schwinn, skinny aluminum rims, and it does make those tires look fatter. I'd think something like a Thick brick wouldn't look much different either way since they're already pretty fat! -Adam

 

[deorman]

I think it varies by tire and application, but bigger tires on narrower rims don't necessarily look bigger to me, just oversized.

 

[Road Master]

My Turn! On my current Build-Off bike I started with standard width rims for 2.125" tires - let me call them "S-2 Style". I put a pair of Fat Franks on them which are 2.35" and they looked pretty fat but the important thing was I had no clearance problems. One thing I would like to note that even if the rims are perfectly true I adjust them after the tires are installed - much like balancing an auto tire but if I just throw it on there the tire doesn't run true so I adjust the spokes till it does. Later in the build I purchased a pair of rims w/ 12 gauge stainless spokes mounted on 2.35 alloy rims. By installing the tire on wider rims I ended up with a larger total width and I immediately had problems with clearance. I trieda myriad of techniques I read here on RRB plus a few original ideas of my own and eventually got the clearance I desired. So from my experience tires LOOK fatter on smaller width rims but ARE fatter on larger width rims. And that fine tuning I referred to after the tire is mounted was very important. I did not torque, bend or reshape the frame at all. This is just my experience - you just keep working on it till you figure it out. Good luck and have fun doing it.

 

[deorman]

I usually try to keep my rims true, and just ignore tire anomalies, but truing the entire wheel, tire included, provides greater efficiency in use. I've been told it was common practice on old time velodrome bikes. Stick that on your "boardtracker" and ride it. :mrgreen:

 

[Verrt]

What would you say the narrowest possible rim you could put something like a 26 quick brick on?

the front rim is considerably wider. do ya notice much of a difference?

What size is the rear rim on this one?