new 94' VX owner, several "advanced" questions!!! lol...

[theholycow]

Originally Posted by mnstrvx

Would a front air dam, lowering the car, getting "air dams" for the front wheels make any difference?

Possibly.

I was thinking of getting a set of lowering springs (just a slight "drop", nothing major) and replacing the tired shocks/struts

They'll never pay for themselves in FE gains. If you want them for fun, enjoy.

whats hypermilling everyone?

It's the practice of trying to exceed the EPA FE ratings. It includes the modifications you're asking about, but mainly it consists of the driving style changes we discuss here.

[Scott Williams]

I'm always reading on hypermilling suggestions about over-inflation of tires, but so often I read about the downsides on "recommended tire inflation" instructions. And that is that over-inflation can cause some erratic and dangerous handling issues in wet weather. Have any of you who commonly inflate the tires to the sidewall max had any problems like that? Rainstorms can come up quickly, and I don't see myself getting out of the car and lowering pressures when a downpour saturates the highway. Also, having been in a 10 car pileup when the roads were slick has tended to make me more cautious. Any thoughts?

Scott

[theholycow]

I've been "over"-inflating for 400,000 of my >600,000 miles of driving experience. I experimented and found it to solve many of my tire problems and concerns long before I had any interest in saving gas. The common fears usually do not materialize. It does differ from one driver/car combination to the next.

The best way to find out what works for you is to experiment. Try different pressures. The car's posted pressure is the minimum safe pressure and the pressure stamped on the side of the tire is the maximum (there are some exceptions but maximum safety is between those two pressures). Each time you adjust it, try to gauge how it's working for you; feel the ride and handling and pay special attention when it rains.

It is usually said that the center of the tire tread will balloon out when overinflated. If that's truly the case, then it will improve hydroplaning-resistance, becoming safer for your particular concern with sudden downpours.

The only time I've found wet traction to suffer from additional inflation is with the rear tires on my pickup. The truck is labeled 35psi, and the LT245/75R16E tires are rated for up to 80psi. With no load in the bed and the tires up to 80psi, the rear tires can spin under moderate acceleration from low speeds. At 70psi they're fine. What do you drive, and what size tires does it have?

[nowhhs]

I haven't noticed much of a difference with my tires at 44psi when its wet, but when there is snow on the roads, I definitely do. I routinely lower my tire pressure when I have to drive in the snow. That also leads me to believe that even though I might not notice any difference in the rain, there nevertheless is one.

[mnstrvx]

i forgot to mention that the AC has been on constantly since I purchased the VX. Here in Phoenix, it's already approaching temp's of 100 degrees!

[palemelanesian]

A nasa study concluded that hydroplaning decreases as tire pressure increases. The speed at which hydroplaning occurs is higher with higher tire pressures.

http://www.tirerack.com/tires/tirete...e.jsp?techid=3
They only explore inflation below the specified 35 psi, but physics doesn't know any such limits. If it's worse below, you can extrapolate that it's better above.

Snow, on the other hand... see above.

[jmf]

Everyone should be slowing down in bad rain storms. That solves hydroplaning.
justin

[Scott Williams]

Hey everyone, thanks for your input on the inflation issue. I'm driving a '92 Honda Civic VX with P165/70R-13 Sumitomo HTR T4. The sidewalls state an inflation of 51 lbs max. That seems like a lot. I have traditionally overinflated 4 lbs with no problems but with your comments, will push that and try more.

And a message to our original poster mnstrvx in this thread. Congrats on the new VX!!!!!!! Didn't mean to take away from your questions.

Scott

[mnstrvx]

scott- the inflation thing was news to me too! I always ran "about" 32-35psi in my car tires... my girlfriend has a yukon with LARGE tires, i might try to inflate those to or near the recommended max.

[theholycow]

If the Yukon has the stock tire size, it can almost surely go to 44psi without any adverse effects.