Car and Driver did a good comparison of the effect of bigger rims on performance. In short, bigger rims with lower profile tires cost more, weighed more, slowed acceleration, improved cornering, and decreased mpgs:
The only real problem I see here is testosterone permeating through the thread… {:-0
I think that the cool tires just had less pressure. if it was tested before when the tires were warmed up, I don t see the big mystery…
I found some literature that goes into excruciating detail on tire inner liner permeability. What I found surprised me and is cause for me to change my position on the subject. What I failed to account for was the variation in liner construction from manufacturer to manufacturer and just how poorly some tires are constructed with regards to the butyl rubber liner. This would explain why some people have tires that can sit for decades without going flat while others may do so in a year or two, regardless of the wheel or valve seal. It was eye opening for me.
There is also a strong argument for eliminating water vapor and oxygen from the fill gas in this article. I know a lot of people, myself included, have ridiculed the use of nitrogen in tires as superfluous but it appears there are instances where it is beneficial, especially in the brands that leak like sieves, relatively speaking…
You can read it yourself here:
Some interesting excerpts (bolding is mine for effect):
The actual permeability measured for the innerliners at 21�C and 65�C was similar to literature values for compounds with high butyl content, but measured higher than literature values for compounds with no butyl content (natural rubber). However, plot against butyl content alone cannot capture the effects of other constituents in the innerliner such as fillers and oils, which vary from one liner formulation to another. The average permeability of an innerliner at 65�C was over 500% (6X) higher than its permeability at 21�C (1.14E-07 versus 1.83E-08 cm^2/(sec*atm)).
Look at the variation in “quality” of various liners they tested. There are orders of magnitude difference in quality:
Permeability
(cm3cm/(cm2s*atm
Liner #1 7.04E-09
Liner #2 7.00E-09
Liner #3 2.03E-08
Liner #4 5.53E-09
Liner #5 2.14E-08
Liner #6 4.61E-08
Liner #7 7.97E-09
Liner #8 8.67E-09
Liner #9 5.25E-09
Liner #10 1.02E-08
Liner #11 5.03E-09
Liner #19 5.32E-08
Interesting. Minimum permeability was 5.03e-9, max was 5.32e-8, 11X higher.
That article also refers to another study that seems to conclude that pressure loss isn’t much of an indicator of tire performance when it compared different tires:
“Waddell (2006-07) found strong correlations between innerliner permeability, or whole tire air loss rate, on intra-carcass pressurization, belt edge separation, and time to failure in roadwheel durability test (both with and without accelerated aging), among tires of the same design with varied innerliner formulations. However, he found no correlation between inflation pressure loss rate and performance in a stepped-up load roadwheel test across dissimilar models of new tires from different manufacturers. Therefore, the research implies that construction features of the tire beyond innerliner permeability and air loss rate also strongly factor into the performance of the tire during roadwheel testing.”