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Old 05-29-2009, 04:03 PM   #31 (permalink)
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Originally Posted by Eddles View Post
Okay, let's look at my manual here. Feast your eyes on the unladen front tire pressures for the Y17DT engine on the leftmost column. It is all 35 PSI no matter what tire is used. The 61 PSI tire is just the "space saver" spare. Now look at Y17DT (ECO4). Now it says 41 PSI. Tell me why can't a Y17DT owner inflate his/her tire to 41 PSI? It's the exact same car. Also note the pressures for the ECO4 rear tires when fully loaded? It says 49 PSI. If it's really unsafe for me to run my tires at 49 PSI, why would a manufacturer of the 2nd most common car in the UK that weights only 2,500 lbs recommend this?
Now, now, you have to tell the whole story!! Notice also that the 2 tires listed for the ECO4 are completely different in tire size than the others listed. Why is that?

Obviously this is a different model and the tire sizing / pressure issue is only part of the story.

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Old 05-29-2009, 04:17 PM   #32 (permalink)
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Could the ECO4 tires be AA rated for traction?

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Old 05-29-2009, 04:17 PM   #33 (permalink)
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The Y17DT ECO4 is exactly the same as the Y17DT but with some areodynamic bits stuck on (spoiler and underbody panels), low ratio gears, and fuel efficient tires in those sizes.

The official marketing name for "Y17DT" is:

VAUXHALL ASTRA LS DTI

The official marketing name for "Y17DT ECO4" is:

VAUXHALL ASTRA LS ECO DTI

"LS" is the trim level - the "ECO" is just a slight variant to the trim level with the changes I mentioned above. If you look at the specs in the handbook, LS DTI and LS ECO4 DTI has the exactly the same information throughout, the only difference is the tire pressures. Even the kerb weight shown in the manual is the exact same for both models. As you can see, all different trim levels/engines has different weights.
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Old 05-29-2009, 04:31 PM   #34 (permalink)
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Yeah, I wouldn't put too much stock on the tire pressure listed in the book or door plaque as they are the recommendations for the stock tires. My car lists 32 PSI and the stock tires had a max sidewall rating of 35 PSI. Now I have tires that have a sidewall max of 51 PSI that I just filled up to ~50; going back to 32 PSI will reduce my FE by ~5 MPG.

Get the tires you want, fill 'em up as far as you feel comfortable.
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Old 05-29-2009, 11:48 PM   #35 (permalink)
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This whole discussion has been a regular hoot! But in the process of researching info for making an informative reply, it seems there is a lot of grey area in this whole issue. Other discussions on this forum point out that 50 psi seems to be the happy medium between not enough braking and cornering and too little air to get good FE.

To be quite honest, I never did put much stock into the recommended psi on the placard and just filled to maximum sidewall. I've occasionally overfilled to 50, but only with a bit of trepidation. One guy I knew had a Ford F-250 Powerstroke that he managed to drive like a maniac and still get 19-20 mpg out of. And this wasn't no eco vehicle either. It had a crew cab, full length bed, 4WD, the lot. But anyway, he put his tires up to 80 psi, and he had a heckuva time stopping that thing in a timely fashion. That and it rode like it had hard rubber tires from a forklift. You hit a ant and I could tell you what it had for breakfast by listening to the ensuing rattles. I think he took it a bit far
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I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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Old 05-30-2009, 04:59 AM   #36 (permalink)
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Quote:
Originally Posted by ShadeTreeMech View Post
This whole discussion has been a regular hoot! .........
I agree, but I'll bet for different reasons!


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Originally Posted by ShadeTreeMech View Post
............



One guy I knew had a Ford F-250 .........he put his tires up to 80 psi, ........
And this is one of MY reasons.

F-250's require the use of LT metric tires - and many of them are DESIGNED to use 80 psi - even says so on the sidewall. It is interesting that he had some issues with them at that pressure.

And just for the record, 80 psi is probably much more than what the vehicle placard calls for!
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Old 05-31-2009, 01:35 AM   #37 (permalink)
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I'll bet 80 psi was way more than what was called for too.

Riding in that thing on the pavement was like riding down a dirt road in a regular car. It was just downright rough going. I'm all for saving fuel, but the damage that was possible by overworking the suspension like that would likely cancel out any fuel savings.

I am curious whether anyone has tried putting on 4 pizza cutter spare tires on their car to save gas. It would certainly offer very low rolling resistance, but wow, I'd hate to take a corner with that arrangement.
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I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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Old 06-01-2009, 12:19 PM   #38 (permalink)
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LT metric Load Range E tires are rated at 80 PSI. Load Range D is 65 PSI. Load Range C is 50 PSI. The truck was designed to handle the load the tires can take. Most people won't run them that high unless loaded. If the truck is loaded down 80 PSI doesn't ride that bad. Unloaded the contact patch gets mighty small.

Don

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