ECO-Fit DiscussionThreads discussing the pursuit of ultimate economy, hypermiling techniques & maximizing your MPG
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Well, the tire people had them at 41psi and they felt almost flat. So, I immediately pumped them up to 60psig and it felt like they were at 32psig, even the sidewalls were not stiff. I decided to pump them up to 70psig and they felt a little more firm but the glide was still not where I wanted. I decided to pump them up to 75psig and I didn't really notice a difference from 70-75psig when driving. I returned to the pump one last time and thought I would try 80psig. At this point, the air pump that I was using was at a gas station and it was giving me hell by not wanting to supply air or fit on the valve stem correctly. It had me a little worried that maybe 80psig was too high and I decided not to go any higher. I know some of the guys on clean run higher than that but I do have my limits Now, that I have drove about 1.5k on the tires at 80psig I have put them through all my daily tortures including rain, cold and upper 70degree weather. The tires are obviously made of a softer compound and they have handled the psig with no problems. I will more than likely leave them at 80psig. I have noticed that everyday I am able to coast a little further than I used too when they were new and very sticky.
Oh, I still have your K&N filter. I just need to recalibrate the SGII since I took it to Disney World in the CRV and figure out if the WAI is worth a damn in the FIT. The new tires would definitely skew the results.
Also, I notice today and yesterday that I was not able to get as good mpg and I am betting the 70degree weather is hurting me with my full grill block in as well. Hell, we are suppose to have 70degree weather next week, warm christmas.
__________________
stock and lame
slow and steady wins the race
Well, the tire people had them at 41psi and they felt almost flat. So, I immediately pumped them up to 60psig and it felt like they were at 32psig, even the sidewalls were not stiff. I decided to pump them up to 70psig and they felt a little more firm but the glide was still not where I wanted. I decided to pump them up to 75psig and I didn't really notice a difference from 70-75psig when driving. I returned to the pump one last time and thought I would try 80psig. At this point, the air pump that I was using was at a gas station and it was giving me hell by not wanting to supply air or fit on the valve stem correctly. It had me a little worried that maybe 80psig was too high and I decided not to go any higher. I know some of the guys on clean run higher than that but I do have my limits Now, that I have drove about 1.5k on the tires at 80psig I have put them through all my daily tortures including rain, cold and upper 70degree weather. The tires are obviously made of a softer compound and they have handled the psig with no problems. I will more than likely leave them at 80psig. I have noticed that everyday I am able to coast a little further than I used too when they were new and very sticky.
Oh, I still have your K&N filter. I just need to recalibrate the SGII since I took it to Disney World in the CRV and figure out if the WAI is worth a damn in the FIT. The new tires would definitely skew the results.
Also, I notice today and yesterday that I was not able to get as good mpg and I am betting the 70degree weather is hurting me with my full grill block in as well. Hell, we are suppose to have 70degree weather next week, warm christmas.
Not having any bench racing this morning we pumped tire pressures up to 80 psi to see what pb&h is talking about.
We haven't had so much fun sliding around since we coated a customer's tires with Mobil 1. At even low sopeeds on track the Fit refused to turn in rapidly and refused to get within 10 mph of our usual 35 mph first turn. We did 4 wheel drift the Fit thru most turns. Whatta ball but drive that way on the street: no way.
Either pb&h drives around at 10 mph, and very carefully then, or he has the worst tires ever seen, or he's just jacking us around, he absolutely has no idea what he's doing.
Haven't seen tires with that little adhesion since Bayer tried their urethane tires that would last a lifetime.
For those of you who care, tires are supposed to bulge at the ground so there is some give to keeping the tire tread as much in contact with the road as can be gotten. All pb&h is doing is reducing the effort to turn the steering wheel and that naturally happens at the expense of traction.
I think old pb&h is jacking us around.
I can understand where you are coming from and why you would make those statements. I wouldn't believe it unless I did it either. The stock Dunlops have not been past 66psig and they were hard as a brick. The ride was harsh/rough and I had no reason to go any higher. Also, the Stock tires handled fine at those psigs. Now, these Kuhmo's are another story, thus far. The Kuhmo's are very soft and sticky. If you noticed I increased the psig in increments so I could see If the handling of the vehicle was compromised. For my terrain and driving style I have not noticed any compromises so far. The ride is still NOT as harsh as the stock Dunlops. The reason I replaced the stock Dunlops before the wear bar was due to traction loss especially in the rain. I honestly didn't think I would be riding on tires at 80psig.
Again, I have no reason to pull anyone's leg on here. Also, I have not recommended that others follow suit. I believe driving style, tires, wheels, modifications and terrain are all major factors that will contribute to how one chooses tire inflation pressures. As far as my driving style, I hypermile like a mofo. I P&G constanly using my FAS switch(thanks to Paul!) and my speeds range from 50-60mph for the "pulse" down to 30-40mph for the "glide" and I take corners when ever I can without brakes at speeds of up to 30mph. I try to hit exit ramps at 50mph if possible. My daily commute to work is 60miles one way which can take me up to 90mins depending on my P&G ranges, stop lights and traffic. Again, I have not said that this is for everyone.
What I would recommend is to test out sidewall max and go from there to your liking.
__________________
stock and lame
slow and steady wins the race
Shawn, When you soft and sticky I'm wondering how much. My sport drag racing we use a gauge called a durometer that can measure that. If you can get by a good shop, measure that on those tires.
Back to the pressure, as an engineer I was just wondering about that pressure. Considering the wheel and valve stem in addition to the tire itself. I always felt fine with sidewall pressure + some margin, but 150% could have some issues you may not have seen yet. Liability wise no one would endorse that and some of the stuff posted on Clean does not tell the entire tail. ie half truths. Just saying this to make you 2nd guess yourself and be safe
Paul, thanks for looking out. I also agree with you about the clean forums which is why I need to see for myself. I just felt the side wall of the tires and they still feel a little soft. I would have been scared to take the Dunlops this high in fear of popping them. These Kuhmos appear that they could easily go to 100psig. The valve stem does have me somewhat concerned, because I do not know what kind of pressures they can hold nor what they are designed to hold. I am not sure if the Valve stem is a weak link in tire set up or not.
As far as durometer, on my skateboard wheels I roll at 99A. I will have to see what I can find to measure these tires.
__________________
stock and lame
slow and steady wins the race
You can read the year and week of the year the tire was manufactured on the side of the tire. 0632 means the tire wasproduced in the 32nd week of 2006.
You can read the year and week of the year the tire was manufactured on the side of the tire. 0632 means the tire wasproduced in the 32nd week of 2006.
That was in the video with the detail needed
__________________ Paul 2008 VBP Fit Sport Man 5 spd trans
208US Gal saved in the last 20,000miles
Just an update the tires rolling at 80 psig are doing great after about 5300miles. Looks like even wear to me assuming there is some wear.
What size tire and wheel are you using? If your rim width is wider than stock and you are using stock size tires the extra pressure may be needed to just flatten out the tread against the ground.
Well, the tire people had them at 41psi and they felt almost flat. So, I immediately pumped them up to 60psig and it felt like they were at 32psig, even the sidewalls were not stiff. I decided to pump them up to 70psig and they felt a little more firm but the glide was still not where I wanted. I decided to pump them up to 75psig and I didn't really notice a difference from 70-75psig when driving. I returned to the pump one last time and thought I would try 80psig. At this point, the air pump that I was using was at a gas station and it was giving me hell by not wanting to supply air or fit on the valve stem correctly. It had me a little worried that maybe 80psig was too high and I decided not to go any higher. I know some of the guys on clean run higher than that but I do have my limits Now, that I have drove about 1.5k on the tires at 80psig I have put them through all my daily tortures including rain, cold and upper 70degree weather. The tires are obviously made of a softer compound and they have handled the psig with no problems. I will more than likely leave them at 80psig. I have noticed that everyday I am able to coast a little further than I used too when they were new and very sticky.
Oh, I still have your K&N filter. I just need to recalibrate the SGII since I took it to Disney World in the CRV and figure out if the WAI is worth a damn in the FIT. The new tires would definitely skew the results.
Also, I notice today and yesterday that I was not able to get as good mpg and I am betting the 70degree weather is hurting me with my full grill block in as well. Hell, we are suppose to have 70degree weather next week, warm christmas.
Any of my tires drive like wooden wheels at 80 psi. You sure you have a real tire pressure gage? Who made it?
im the assistant manager of the discount tire co. in huntsville, tx. i have an 08 fit with 17'' and no matter what size your tires are you shouldn't go over 40 and i would never go over 35. your tires will start to wear in the middle really fast and no matter what the tire's max is the valve stems are only rated to 50 psi. 35 is perfect for all passenger tires, unless you have really low pros you should run 40.
im the assistant manager of the discount tire co. in huntsville, tx. i have an 08 fit with 17'' and no matter what size your tires are you shouldn't go over 40 and i would never go over 35. your tires will start to wear in the middle really fast and no matter what the tire's max is the valve stems are only rated to 50 psi. 35 is perfect for all passenger tires, unless you have really low pros you should run 40.
While what you suggest is the normal way to treat tires and pressure for daily street driving there are obviously some people that think that they will do OK using very high tire pressures. So far they are not getting problems but I think that it would be dangerous to do very high pressures- as in unsafe for me or my family. What is the point when gas prices are about $2.25 per gallon or less. Do you really want to get into an accident over this?
These are not high pressure bicycle tires you are pumping up. The tires were not designed for use with the Fit at pressures that high. 35 to maybe 37 is high enough.
I guess one of these owners will need to get into trouble before they will find that it doesn't make sense to do what they are doing but it is now a long time that several people are doing this and they continue to do so.
Just keep in mind that if the tire blows out or you loose control and an accident occurs, you can be asked how the pressure in the tire was and an investigator can check the pressures in the remaining tires to find that they are way too high. You can then be found responsible for the accident and any harm they might be to people or property.
From Cars.com
If tire pressure is too high, then less of the tire touches the ground. As a consequence, your car will bounce around on the road. And when your tires are bouncing instead of firmly planted on the road, traction suffers and so do your stopping distances. You'll also feel a decrease in ride comfort. (Hint: If you notice that every tie you own has coffee on it, check your tire pressure. It may be too high.
Another tire site mentions-
High tire pressures may cause reduced comfort, less grip, greater risk of impact tire damage and reduced stability in braking and cornering.
im the assistant manager of the discount tire co. in huntsville, tx. i have an 08 fit with 17'' and no matter what size your tires are you shouldn't go over 40 and i would never go over 35. your tires will start to wear in the middle really fast and no matter what the tire's max is the valve stems are only rated to 50 psi. 35 is perfect for all passenger tires, unless you have really low pros you should run 40.
As a retired tire engineer let me add that tire pressures are dependent on the wheel you are using. The wider the wheel rim the higher pressure required to 'flatten' the tread. The flatter the tread the better wear you will get. The same tire on a 5" rim width will take less psi than that tire on a 7" wide rim. The tread is never truly flat but in rotation the tire will make it so even if it is seen only by high speed cameras.
The only reason to go over 40 psi is when high performance is required to minimize tire deflection and deformation, both of which deteriorate performance where wear is of no concern.
Going more thasn 50 psi diminishes performance as the tire patch is significantly reduced.
As a retired tire engineer let me add that tire pressures are dependent on the wheel you are using. The wider the wheel rim the higher pressure required to 'flatten' the tread. The flatter the tread the better wear you will get. The same tire on a 5" rim width will take less psi than that tire on a 7" wide rim. The tread is never truly flat but in rotation the tire will make it so even if it is seen only by high speed cameras.
The only reason to go over 40 psi is when high performance is required to minimize tire deflection and deformation, both of which deteriorate performance where wear is of no concern.
Going more thasn 50 psi diminishes performance as the tire patch is significantly reduced.
That reduced tire patch is what is useful in gaining mpg when used with excessively high pressures.
The safety issue is with reduced traction, how likely is one to loose control and get into an accident. Another issue is if the tire strikes a curb with high pressure it's more likely to be damaged to blow out. What about hitting a pothole? More likely to damage the rim or suspension? Depends how big a pothole and how fast you are going. And finally comfort- you could get better mpg with wagon wheels but ride quality for daily use could be a bit rougher.
If you ran high pressures but drove really carefully you might do OK. If the road is slick or icy or if there are any debris or hazzards, you might be at added risk.
You should do more research or try it out. I have ridden with patched tires and with a nail in my tire at 66psi on the stock Dunlops.
Traction is improved in dry and wet conditions. Of course there is always a limit.
Tires lasting longer remains to be seen in my book. I am on set 2 so I will see if they make it past the 60k mark as manufacture states.
Valve stems rated at 50psig is good to know but then the questions remain:
how much can it hold and are there standards or differences in the the valve stems? (I know they can easily hold 85psig and some have said easily 100psig.)
__________________
stock and lame
slow and steady wins the race
I know some of the guys on clean run higher than that but I do have my limits
Now, that I have drove about 1.5k on the tires at 80psig I have put them through all my daily tortures including rain, cold and upper 70degree weather. The tires are obviously made of a softer compound and they have handled the psig with no problems. I will more than likely leave them at 80psig. I have noticed that everyday I am able to coast a little further than I used too when they were new and very sticky.
-CleanMPG.com, the real Eco forums.
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