94 Civic VX - Not great MPG

[add|ct]

^Ha, thanks for fixing my mistake. I couldn't recall off hand and I do believe the number from perhaps the same site thc is referring to, did in fact say 975. I knew it had 75 in there.

So, if with 175/70/R13 the speedo reads 60 MPH and I change back to stock 165/70/R13, 60 on the speedo would mean 58.5 MPH?

I still don't know if it's worth it to go back to 165 other than price. Any advantage to get away from the 175s gentlemen? I'm welcome to opinions and advice, especially in the interest of fuel economy. I want the Sumitomo's since they can be had in the OE size 165, and it's max sidewall PSI is 51. I'll be right there at it.

[theholycow]

Originally Posted by add|ct

So, if with 175/70/R13 the speedo reads 60 MPH and I change back to stock 165/70/R13, 60 on the speedo would mean 58.5 MPH?

Yes, if the speedo is currently accurate. I imagine it's currently reading 60mph when you're really going 61.5, and after putting on stock-size tires it'll read accurately.

[benfrogg]

Add-
I ran 175's before these 165's and I saw a slight improvement in FE/ torque compared to the 175's. The extra 2.5% or whatever made it slightly harder to maintain lean burn which made it get slightly less FE. (as opposed to the common idea that bigger is better because of less rpm per given speed) It seems that Honda had the gear ratios just right with the 165's. That's why I say go with them.
To note, I was correcting for my % off by adding 2% to the odo reading before.

Also; in theory HC is right about the speedo. In practice however, the VX speedo (like many other hondas of this vintage) reads about 1.8 miles per hour too slow. You'll find that a GPS slighlty disagrees with your actual speed if you change to 165's. It likely is very close right now to actual.

I run my sumitomos at 65 psi. No issues and they seem to handle well at that pressure. Their snow performance is impressive for an all season, as is their summer/wet performance.
B

[paulhale]

Originally Posted by benfrogg

I run my sumitomos at 65 psi. No issues and they seem to handle well at that pressure. Their snow performance is impressive for an all season, as is their summer/wet performance.
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Man, that still just seems way too high. I was nervous getting mine to 45 psi. Guess I'm just oldschool. I'm used to following the sticker in the car's doorjamb, so going much over 30 psi just sounds crazy.

[add|ct]

I'm still a noob, so I won't run above 51 PSI; and will probably rotate every 5,000 miles or so. Not exceeding 6,000 if possible.

Thanks for the tips on alignment. It makes me less reserved in going back to 165s.

I had an independent local shop quote me $355 out the door for 4 new installed, lifetime balance and rotation. Good deal? Sumitomo HTR T4s, 165/70/R13.

[benfrogg]

Here's tire rack,$55 a tire plus shipping.

http://www.tirerack.com/tires/tires....k&autoModClar=

$220 + $43 cheap shipping=
$263
Probably $50 to have them swapped over, out the door $313 or so.

Save a couple bucks, I guess. I did it this way but that was because the locally owned place couldn't get sumitomos.
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[add|ct]

^Add $20 to that to include tax and 'per tire' fees. So, $333 by that if I use a shop to just mount and balance. I figure $27 more out the door for lifetime balancing and rotation is worth it?

Thankfully this locally owned place can get this Sumitomo in particular.

Speaking of Sumitomo and relative to this thread, anyone used the HE76 NGK(8034) cables with success on these VX engines instead of the Sumitomo?

[imzjustplayin]

Originally Posted by paulhale

Man, that still just seems way too high. I was nervous getting mine to 45 psi. Guess I'm just oldschool. I'm used to following the sticker in the car's doorjamb, so going much over 30 psi just sounds crazy.

I wouldn't worry about it... tires are far more likely to burst due to low pressure than from high pressure. The reason for this is that tires with too low of pressure will flex and deform too much causing them to overheat and in the worst case disintegrate and burst. Another benefit of higher pressure is that if you hit a curb and destroy your tire, you'll at least protect your rims. Brand new tires have been burst tested well over 300psi with usually the tire rims failing before the tire failing.

[benfrogg]

I just recommend people put as high a pressure in as they dare/can handle the ride changes. I started low too, 40-45psi. Over time, I "graduated" to higher and higher pressures. Now it's been over a year with 60+psi all around. Some of that comes from tires that have 51psi max sidewall pressure. Note that my rear tires are currently pirelli p3000's that have a max pressure of 35psi. I keep them lower than the front for that reason.

Anyhow, I suspect the OP will be much better served keeping the tires at 45psi because it will keep them above sidewall pressure for longer. I do highly suggest keeping a magnetic air gauge somewhere like the gas door or other frequently used area (in my case that would be under the hood too, I seem to have that open more often than my gas cap!) to remind you to check it and fill them often.

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[paulhale]

I should be doing a fill-up after work today. I will report back with the new MPG.

In other news, I pulled off my PCV valve to check it. Unfortunately, the grommet underneath is so brittle that the PCV valve doesn't really sit as snugly as it should. I'm going to go ahead and replace both the valve and the grommet ASAP. I'll probably order an EGR gasket at the same time. I am hesitant to remove the EGR without having a new gasket on-hand.