VX benefits from LRRs

[james]

I put 2 sumitomo htr t4 LRR tires on my 94 vx a couple of weeks ago. It makes a much larger difference than I would have guessed. The first tank has yielded 62.6 MPG and this one looks similar so far. I will have to do a few more tanks and see what she gets in the summertime to really be sure of the exact benefit. This 62.6 MPG included carrying a several hundred pound load for part of the tank, and cold weather, snow and ice. My guess so far is that they make a 6-8 MPG difference. that is only for 2 tires! I guess my old ones were cheap, damaged, too large, and not LRR.

The car stays in lean burn much longer. Part of this is because I switched from 175/70/13 to 165/70/13, making the engine spin a little faster. It drives smoother, faster, and stays in lean burn on the highway almost the entire time.

[KJSatz]

Does your odo know the tires are a different size?

Anyway, congrats on the improvements! I'm definitely going to give LRR tires a long look next time.

[hypermiler01]

Originally Posted by KJSatz

Does your odo know the tires are a different size?

Ya, are you calculating the fact that when you put smaller tires on, your car is not going as many miles as it thinks it is. In your case, you are losing 2.4% of the miles on the odo.

Tire size calculator

Strange thing is that most people get better mileage by installing LARGER tires to decrease RPM.

[basjoos]

The 165/70/13 is the OEM size for the VX and CX. The other 92-95 Civic trim lines had the 175/70/13 as their OEM size. But the 165/70/13 size is harder to find and most tire shops will quote the 175/70/13 when asked about tires for a 92-95 Civic, so most VX and CX Civics are now found with 175/70/13 tires on them.

On my car, I currently have Sumitomo HTR T4 165/70/13, but previously had Michelin Harmony 175/70/13. If anything, I have seen a slight drop in mileage in going to the Sumitomo and a distinct reduction in cornering and braking abilities than the Michelins had. When going from a wider to a skinnier tire, you have two competing effects going on. A skinner tire has less aero drag than a wider tire, but it also has a higher rolling resistance (due to the sharper bend angles of the tread rubber on each side of the footprint) than an otherwise identical wider tire. With most cars, the aero benefits trump the rolling resistance penalty of the skinnier tire, so the skinnier tires gives better mileage than the wider tires. But with my car, I have the tires so well shielded from the airflow that I'm not getting any of the aero benefits, but am getting the RR penalties, so I am not seeing any better mileage from the 165/70/12 tires. When the Sumitomos wear out I will likely go back to the Michelin 175/70/13 for their improved handling. Alternatively I could get a set of 14" rims and mount the Potenza RE92 tires used on the Insight.

[dichotomous]

really? the aero is the benefit to skinney tires? I am definately putting big ol spats or pants on my summer tires, they are 215width and my winters are 205 width, stok is 195, but I like the security of cornering on tires an inch wider all around, they are as wide as dad's 4600lb avalon, so I can corner pretty well on my 2800lb Si

[metromizer]

I noticed a 1-2 mph drop when I replaced the Yokos <the car came with, worn out> with these cheap bottom of the line out-of-round Kuhmo tires. Then I realized a 3mpg improvement when I replaced the Kuhmos <after only 10k miles> with Michelins. Neither tire sets were LRR, but the Michelins are rated as a 60k tire for my Metro>

[orange4boy]

Skinny tires are also reduce hydroplaning and water resistance. (given the same tread pattern)

You can really see the difference RR makes in the P+G table by newtonsfirstlaw.

I'm still looking for LRR tires for my Previa. 205 75 14 or thereabouts.

[james]

Like basjoos said, the 165s are actually the stock size...so the odometer was off before and is correct now (I checked it on the hwy). I think the 165s are a couple of pounds lighter, which helps in the city. I find the handling is fine with the sumitomos...not amazing, but I dont ask the car to do too much. The skinnier tires are better in the snow too, I can tell the difference. Last winter with the wider and partially worn down tires on the back, I had the back end slide out around a corner. It was a downhill slope and there was no weight in the back. the back of the car is very light when the tank is empty. I was only going 10 mph! So now if I have any weight I put it in the way back, when the roads are snowy.

[james]

The 165s are easier to turn without power steering too.

[backsidesnap]

I have been looking around to buy a set of sumitomo htr t4's for a long time. And it seemed that tirerack was the only place to find them. then I found onlinetires.com and they have them at 39 each for the stock vx size. and the shipping is ten bucks less. Just ordered them tonight, but im excited to have lrr's in the stock size!