Tire Engineer here - concerned about hyperinflating tires

[SVOboy]

But there's diminishing returns for anything related to fuel economy, that's not a new idea, nor do I think it's important to the question of safety.

[trikkonceptz]

Wouldn't the optimal efficiency of a tire be contact patch size equals tire size?

Meaning if your vehicle has 185 / 60 / 15 then the patch size should be 185mm. I heard a way to measure this using a simple string around the bottom of the tire and some formulas. I'll dig it up and post it to see if we can prove it true.

[JohnnyGrey]

But there's diminishing returns for anything related to fuel economy, that's not a new idea, nor do I think it's important to the question of safety.

It is important to safety because as you start to overinflate, MPG gains level off and your safety starts to fall off rapidly to the point where you're giving up a lot of safety to secure a very small amount of economy.

Some of the guys on the Cavalier forums think I'm insane for running my 44psi max tires, at 44psi. Granted, they might be on the other extreme, but do you really want to find out how thick the margin of safety is on your tires? Remember that this margin accounts for manufacturing variances that can't easily be quantified. Just because so and so was fine running at 25% over, you might not be so lucky.

[ihatejoefitz]

Originally Posted by JohnnyGrey

It is important to safety because as you start to overinflate, MPG gains level off and your safety starts to fall off rapidly to the point where you're giving up a lot of safety to secure a very small amount of economy.

At what psi? Sources/data?

[trikkonceptz]

I came across this link: http://www.performancesimulations.co...on-tires-1.htm

It doesn't really answer our questions, but the data collected by the tire manufacturer does illustrate the varying contact patch size in relation to load and PSI.

[dremd]

Originally Posted by CapriRacer

I've been reading about folks inflating tires over the maximum printed on the sidewall and this is one site where this has been reported. I've joined just to add technical background as to why that is a bad idea!

Sweet!

Could you please provide some technical background as to why it is a bad idea?

[larryn2o]

i run 175/50r13 tires , recommended max inflation is 51 PSI . not sure if they qualify as low rolling resistance , but i like the way they look.

[trikkonceptz]

I think we were just taken for a ride folks .. funny how our "tire Engineer" hasn't been back on since the post and really didn't give us any information with his first post.

I think he wanted to spark some argument and was dissapointed when we began a rational conversation ...

[Johnny Mullet]

^ I agree!

[Randy]

Originally Posted by trikkonceptz

I think we were just taken for a ride folks .. funny how our "tire Engineer" hasn't been back on since the post and really didn't give us any information with his first post.

It's too bad really. Tires seem to be pretty complex... they aren't just balloons. I don't think we'd ever settle these arguments without some more understanding of what exactly is going on. Even simple ideas like choosing the lowest rolling resistance tires seem to be complicated by the tire size and pressure.