![2.8 inches actual size 2.8 inches actual size](https://i.pinimg.com/originals/93/45/ca/9345ca6e2b04cbc4fb3b41d8608e9a0e.jpg)
Let's not kid ourselves, a 2.8" tire is five mm thinner. 2.8"s (and 2.6) came to pass so ppl wouldn't be as scared to try a plus tire without being made fun of for a full 3" wide tire. Over time, technology progressed and now we have a decent selection of tires but the cool kids made up their minds that plus tires weren't cool because of shitty tire design combined with morons running 3" wide tires on i30 rims at 14psi and wondering why the tire flies off the rim. Other companies had similar problems too. Evidence schwalbe tires for weeping sealant on the sidewalls in an attempt to keep the tires light. Plus tires were terrible in the beginning because they were pushed as a design for "new" riders and the casings were made too light for anything other than hard pack.
![2.8 inches actual size 2.8 inches actual size](http://scifimafia.com/wp-content/uploads/2010/03/3inches-ruler-WIDE.jpg)
Stand with one foot on the paper and a slight bend in your knees. In some designs, you'd be more likely to rip off side knobs before you damage the casing in most instances. Tape a piece of paper to a hard floor, ensuring the paper doesn’t slip. A terrene chunk measures 3.1" at the knobs on an i45 rim, and 3" on an i38 rim. If you consider case design, then rim ratio could potentially mean even less. Ignoring casing design, 2.0-2.2 are the ratios people are shooting for. The accepted industry standard for rim widths seems to be settling on i30 for 2.3-2.5 tires and i35-i40 for anything wider. So maybe the recommended rim should be moved over 5mm less for every 0.2 inches of width:Ģ.2 and less = standard 17-23mm rim, mix and match with no issues at these widths and PSI's 1.90x would be exactly in the middle for ratio, and that would be on a 40mm rim, not 45mm. The ratio is much closer to a fat tire than to a standard tire, even if the tire itself measures exactly between them. So why would they have the tire to rim ratio closer to 1.25 than to 2.5?ģ.0 tire on a 44mm rim is 1.67x tire to rim ratio, better than 1.25x, but still not even halfway to 2.54x for the 2.0 tire. The whole point of buying a + tire is NOT to have all of the side effects of a fat tire, with excess float/self steering, inferior cornering, worse/nonexistent side knob traction, etc. But when you start looking at the tire to rim ratio, it's not linear.Ģ.0 tire on 20mm rim is 2.54x tire to rim ratio.Ĥ.0 tire on 80mm rim is only 1.25x tire to rim ratio. So if most 4.0 tires have 65-80mm rims, and 2.0 tires have around 20mm rims, then the conventional wisdom is that + tires need 35-50mm rims. I think what happened after fat bikes is they back-extrapolated the tire to rim ratio from 4.0 inch tires back to 2.0 inches with + tires in the middle, to try and figure out the best of all worlds ratio for the middle tires.