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Old 01-01-2005, 08:49 PM   #1
GC84ever
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Default Too much pressure?

Is this too much pressure for my Dunlop M3's 35F/32R (205/55R16)?
Those meausements were taking in a heated garage. Also When I had them (M3s) installed I asked the guy to use the recommended stock tire pressure, which I guess he must have misread. Or I am such a newb that I can't use a tire pressure gauge.

From the looks of it the front tires bulge out on the road surface enough already, and I don't want to have them "pop" from underinflation.
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Old 01-01-2005, 09:06 PM   #2
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The chances of your tires popping from underinflation are about one in a million. However the bead could break lose. But also highly unlikely at those pressures. And those pressures are fine. However personally I would bump them up for better turn-in, and less sidewall rollover.
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Old 01-01-2005, 10:15 PM   #3
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Quote:
Originally Posted by ratt_finkel
The chances of your tires popping from underinflation are about one in a million. However the bead could break lose. But also highly unlikely at those pressures. And those pressures are fine. However personally I would bump them up for better turn-in, and less sidewall rollover.
What tire pressure would you recommend?
I do find a bit of understeer, but it might be just the road surface condition.
I though the stock 32F/29R would be best since they are the same size as my old RE92.
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Old 01-01-2005, 10:24 PM   #4
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If you check your pressures in a heated garage make sure to add a couple of pounds at least as pressures will fall with the outside temp.
I am in Calgary and set my Hakka Q at 34F/32R in a heated garage. I've not checked them after a night outside and will probably have to bump the pressures up some after I do this.
Perhaps it's just me but I am not a big fan of high tire pressures in very cold weather.
Mike
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Old 01-01-2005, 11:38 PM   #5
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Quote:
Originally Posted by GC84ever
What tire pressure would you recommend?
I do find a bit of understeer, but it might be just the road surface condition.
I though the stock 32F/29R would be best since they are the same size as my old RE92.
I have no expierence with those tires. So I can't really help. That's something you'll have to expierment with.
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Old 01-02-2005, 02:04 AM   #6
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What's the advantage of having higher pressure for the front tires? less understeer? thanks.
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Old 01-02-2005, 10:57 AM   #7
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In winter, a little less pressure isn't a problem and may help traction.....but as temperatures warm up, I'd increase pressures a bit if driving on dry roads.

35/32 should be just fine.
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Old 01-02-2005, 12:26 PM   #8
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Quote:
Originally Posted by ratt_finkel
The chances of your tires popping from underinflation are about one in a million.
The odds are much better than that, depending on what driving and how much you drive.

Haven't you ever watched 5th Gear?
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Old 01-02-2005, 12:39 PM   #9
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Quote:
Originally Posted by RC0310
What's the advantage of having higher pressure for the front tires? less understeer? thanks.
There is more weight on the front tires. Having more pressure in them supports that weight and helps equalize tire wear. Weight distribution is the main reason the front tires on a Subaru wear faster than the rears.
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Old 01-02-2005, 05:53 PM   #10
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Quote:
Originally Posted by ratt_finkel
And those pressures are fine. However personally I would bump them up for better turn-in, and less sidewall rollover.

Quote:
Originally Posted by GC84ever
What tire pressure would you recommend?
I do find a bit of understeer, but it might be just the road surface condition.
I though the stock 32F/29R would be best since they are the same size as my old RE92.
I have no expierence with those tires. So I can't really help. That's something you'll have to expierment with.

this is funny to me!
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Old 01-02-2005, 11:23 PM   #11
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Quote:
Originally Posted by SgWRX
this is funny to me!
Sorry I didn't go into more detail. I just don't believe in manufacturer's "suggested" pressures. As it's a catch all not recommended for every type of vehicle that their tire will be equipped on. And I know that those pressures even in maximum performance tires would be too low for my liking.
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Old 01-02-2005, 11:40 PM   #12
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yeah, geez i hope i didn't sound mean. it was funny taken out of context like i edited the quote.

you bring up a good point. on the one hand we have auto makers suggesting inflation pressures on the other hand the tire maker. but you really can't follow the auto maker because they are not going for the best performance huh? sounds like it really is a trial and error thing for tire and car.
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Old 01-03-2005, 12:01 AM   #13
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Quote:
Originally Posted by SgWRX
yeah, geez i hope i didn't sound mean. it was funny taken out of context like i edited the quote.

you bring up a good point. on the one hand we have auto makers suggesting inflation pressures on the other hand the tire maker. but you really can't follow the auto maker because they are not going for the best performance huh? sounds like it really is a trial and error thing for tire and car.
Not to mention surface, temperature, and driving style.
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Old 01-03-2005, 02:12 PM   #14
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pump it up pump it up
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Old 01-04-2005, 12:52 AM   #15
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What's the max pressure for those tires? 44psi? As long as you don't go above the max, you're fine.

For under inflation, that's more by feel. I personally don't like to see anything below 20psi as tire feel becomes a bit sloppy. Of course, something that low usually means you haven't been checking your tire pressures lately. Anything over 30psi is fine for me.

So, what's right? Well, that's up to you, how you drive, the road conditions, and how worried you are about even wear.

First off, the manufacturer's recommended is only based off a stock car with the specific tires that came on it. It's like that for the weight balance of the car, the handling balance of the car, and even how for how nice the car rides. Once you go to a different brand, this all changes as the new tire will be rated differently and have different handling and feel characteristics. So, what we need is a general rule of thumb that applies for all tires.

Rule of thumb:
Lower pressure -
-softer ride
-mushier handling, more tire flex
-car weight distributed on outer edges of tire
-generally increased traction, especially over rougher surfaces

Higher pressure-
-firmer ride
-improved handling feel
-car weight distributed along the center of the tire
-generally less traction

So, what to pick.
Well, for ride comfort, a lower pressure will feel better. However, you'll sacrifice some handling feel for something a little less crisp and precise.

For wear, you're trying to balance the inflation level to a point where the pressure distribution across the tread is most even. This is hard to tell from sight or feel. In fact, it may require significant tire and tire wear to see if your tires where over or under inflated. Better yet, a temperature reading of the inner, center, and outer points will show how hard each part is working, ie. wearing. I don't know if you'd want to spend cash on such a device just for this purpose, lol.

A couple other things to consider. First, the higher the inflation, the easier the tire rolls along the ground and the better fuel economy you'll get. As well, a higher inflated tire creates less friction with the road, the reason fuel economy increases(not by much really). Less friction also means less heat build up. Heat build up is not good for tires. It's why all those Ford Explorers were getting blown tires. It wasn't a Firestone thing. Ford only did it for comfort and I believe some handling/roll over characteristics. It was the fact they were running a relatevly low pressure on a very heavy vehicle, and when loaded with cargo, there was a lot of friction and heat build up. The tire wasn't designed for that application or at least to be used in such a manner, and the tire failed.


I personally like to just say screw it to the recommended pressures and pick something close to the max the tire's rated for, 35psi on passanger car tires and usually 44psi for the sportier, lower profile tires. For me, it helps with efficiency, improved handling, and to help keep the edges from wearing from spirited driving.
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Old 01-04-2005, 10:22 PM   #16
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GC84ever
Your original post was if your pressures are too high or not. They are not. You did,however,get me thinking and as a result I ran a couple of tests last night.
1- I inflated one of my summer tires to 40 psi at room temperature. Put it outside at -24C for the night.
Checked it this morning and it was at 32.5 psi
Warmed it up inside and it went back to 40 psi.
2- Inflated my snows to 38F/36R in my garage at around 10C
Put the car outside at -24C for the night.
Pressures this morning were 33.5F/31.5 rear.
3- Reset the pressures cold to 33.5F/30.5 rear and took the car for a 1 hour drive(60% highway) . Rechecked pressure hot(if you can call it that) and had 35.5F/32.5 rear.
I have not been paying enough attention to the drop in pressure in cold weather,now I will.
Hope this helps
Mike

Last edited by Mike D02; 01-04-2005 at 11:16 PM.
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Old 01-06-2005, 12:07 AM   #17
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Thanks everybody for your help.
I think I'm going to inflate to 38F/35R, lately I find my tire feel a bit sloppy especially when cold.
I'll post if it make a difference.
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