Are your tires the same final diameter? See this link https://tiresize.com/comparison/. When you switch overall diameter it takes more or less energy and time to roll the same distance. That translates to speedo being off as well. might say 55 in car but your really at 60, yes that slight difference does effect soul mileage.. bugs me too
Changed from 18" > 16" = Performance Loss
So, I changed from:
Stock 18" Alloys and Khumo Tires (235 45r18)
to
16" Steel with Cooper Tires (205 60r16)
I'm losing mpg and acceleration from standing as well as while driving has suffered. Not that I've gone on a long trip yet, but I will soon.
Now I knew and somewhat expected these issues after reading up on what others elsewhere had to say about switching to steel due to the differences in weight.
Thing is, I'm thinking...my old tires are way way heavier than my new ones. I can easily pick up one of my new ones with one hand whereas I can't with the old ones.
I just wanted to know if I was missing something here. Had an alignment the other day mind you...and the tires/wheels came mounted and balanced by the Discount Center. Also, my PSI is all at 33.
Thanks
Stock 18" Alloys and Khumo Tires (235 45r18)
to
16" Steel with Cooper Tires (205 60r16)
I'm losing mpg and acceleration from standing as well as while driving has suffered. Not that I've gone on a long trip yet, but I will soon.
Now I knew and somewhat expected these issues after reading up on what others elsewhere had to say about switching to steel due to the differences in weight.
Thing is, I'm thinking...my old tires are way way heavier than my new ones. I can easily pick up one of my new ones with one hand whereas I can't with the old ones.
I just wanted to know if I was missing something here. Had an alignment the other day mind you...and the tires/wheels came mounted and balanced by the Discount Center. Also, my PSI is all at 33.
Thanks
1 - 19 of 19 Posts
Yeah, I'd measured that prior to purchasing. Total diameter difference was about .32"Are your tires the same final diameter? See this link https://tiresize.com/comparison/. When you switch overall diameter it takes more or less energy and time to roll the same distance. That translates to speedo being off as well. might say 55 in car but your really at 60, yes that slight difference does effect soul mileage.. bugs me too
Is that really enough to make a big difference? Even with acceleration?
Correction: I see from that link you provided that the difference is actually greater? Hmm
------------------------------
The meaning of that statement is unclear. Have you measured your 0-60 or quarter mile? WHAT is your MPG change?So, I changed from:
Stock 18" Alloys and Khumo Tires (235 45r18)
to
16" Steel with Cooper Tires (205 60r16)
I'm losing mpg and acceleration from standing as well as while driving has suffered. Not that I've gone on a long trip yet, but I will soon.
Now I knew and somewhat expected these issues after reading up on what others elsewhere had to say about switching to steel due to the differences in weight.
Thing is, I'm thinking...my old tires are way way heavier than my new ones. I can easily pick up one of my new ones with one hand whereas I can't with the old ones.
I just wanted to know if I was missing something here. Had an alignment the other day mind you...and the tires/wheels came mounted and balanced by the Discount Center. Also, my PSI is all at 33.
Thanks
The difference is diameter and RPM is 2%.
https://tiresize.com/comparison/
Yeah, he used to be able to run 9 seconds in the quarter mile with the 18-inch wheels, and now it's 17 seconds. That's a significant difference in acceleration right there.The meaning of that statement is unclear. Have you measured your 0-60 or quarter mile? WHAT is your MPG change?
The difference is diameter and RPM is 2%.
https://tiresize.com/comparison/
Thanks for the input.Yeah, he used to be able to run 9 seconds in the quarter mile with the 18-inch wheels, and now it's 17 seconds. That's a significant difference in acceleration right there.
So if in fact then this is what Should be expected then I'm fine with that. As mentioned, I had somewhat expected a change prior to getting them...yet originally thought the difference might've been based more upon weight which I see now it isn't in my case.
Wanted to be sure there was not something else fishy going on.
Funnily enough, I got the .32" stuck in my head is how I was measuring the actual difference in the height of the car off the ground from one set to the other. Forgetting that it's half of the full diameter difference. Not that that's necessarily here or there.
As for the MPG, I've no numbers...otherwise I'd be able to compare to those I might have from my 18"...which I don't have either. lol.
I based my observations upon my driving habits and watching the gas gauge drop significantly faster than I'm used to.
Might I add,
The fella at Discount Tire tried to convince me to get the 205 65r16 instead.
I didn't understand fully the reasoning at the time. Now I guess I do. With those tires the difference then would've been -0.6% rpm.
The fella at Discount Tire tried to convince me to get the 205 65r16 instead.
I didn't understand fully the reasoning at the time. Now I guess I do. With those tires the difference then would've been -0.6% rpm.
There is no way there could be any significant performance difference. If anything, with the lighter 16s there should be a marginal improvement in acceleration and MPG. Braking could be a different matter.Thanks for the input.
So if in fact then this is what Should be expected then I'm fine with that. As mentioned, I had somewhat expected a change prior to getting them...yet originally thought the difference might've been based more upon weight which I see now it isn't in my case.
Wanted to be sure there was not something else fishy going on.
Funnily enough, I got the .32" stuck in my head is how I was measuring the actual difference in the height of the car off the ground from one set to the other. Forgetting that it's half of the full diameter difference. Not that that's necessarily here or there.
As for the MPG, I've no numbers...otherwise I'd be able to compare to those I might have from my 18"...which I don't have either. lol.
I based my observations upon my driving habits and watching the gas gauge drop significantly faster than I'm used to.
Car and Driver tested a Jetta with various diameter wheel/tire combos several years back. From 15" to 18" or possibly 19". Smaller, lighter wheels favor acceleration because of less inertia, laws of physics stuff.
Then, if that in fact is the case, I might have other issues?There is no way there could be any significant performance difference. If anything, with the lighter 16s there should be a marginal improvement in acceleration and MPG. Braking could be a different matter.
Car and Driver tested a Jetta with various diameter wheel/tire combos several years back. From 15" to 18" or possibly 19". Smaller, lighter wheels favor acceleration because of less inertia, laws of physics stuff.
Accelerating for me has considerably changed with these new sets. I can feel the engine working harder upon speeding up (thus, the loss in gas?).
Admittedly, until this past hour, I've never understood the purpose of having the RPM gauge. On my trips later today I'll be paying special attention to it while doing some test accelerations. Not that it'll solve my problems but it's a decent first step towards understanding better?
Then, if that in fact is the case, I might have other issues?
Accelerating for me has considerably changed with these new sets. I can feel the engine working harder upon speeding up (thus, the loss in gas?).
Admittedly, until this past hour, I've never understood the purpose of having the RPM gauge. On my trips later today I'll be paying special attention to it while doing some test accelerations. Not that it'll solve my problems but it's a decent first step towards understanding better?
Our test employed nearly identical Goodyear Eagle GT ultra-high-performance all-season tires in all five sizes, inflated to manufacturer-recommended pressures. We say that the tires were nearly the same because the 15-, 16-, and 17-inchers have a lower speed rating (V, or a top speed up to 149 mph) than the 18- and 19-inch tires’ W-rating (up to 168 mph). This, however, was as close as we could get to testing the same tire in every size. We used the stock steel wheels for the 15-inch test and went to the aftermarket for the larger wheels, as most owners would do. The aftermarket wheel we chose was a cast-aluminum ASA GT1, which is available in 16- to 19-inch sizes on the Golf. It’s obvious from the test that as wheels and tires grow in size, they also grow in weight. Here’s how the test shook out:What’s immediately apparent from the results is that as the wheel-and-tire packages get larger and heavier, acceleration and fuel economy suffer. Neither is a huge surprise, but we measured a 10-percent drop in fuel economy and a four-percent degradation in 0-to-60-mph acceleration from the 15s to the 19s, which is worth considering should you be thinking about “going big.” Increasing wheel diameter and width, in turn, requires wider tires with shorter and stiffer sidewalls, which we found will increase skidpad grip, but as our test shows, there is a limit to this assertion. The 19-inch package came with the widest tires (235/35R-19) mounted to the widest wheels (8.5 inches), but this setup had less grip around the skidpad than the narrower 225/40R-18s on 8.0-inch-wide wheels. We asked the folks at Goodyear why that might be, and they postulated that the added width may have given the outside tire more grip, which would increase body roll and could therefore decrease the load on the inside tire enough to lose 0.01 g on the skidpad.
https://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested
Thanks for that. Prior to testing out the car this afternoon, my psi were all 2-3 below where I last had it a week ago. (no clue...) Brought them up to 33 psi each.
Our test employed nearly identical Goodyear Eagle GT ultra-high-performance all-season tires in all five sizes, inflated to manufacturer-recommended pressures. We say that the tires were nearly the same because the 15-, 16-, and 17-inchers have a lower speed rating (V, or a top speed up to 149 mph) than the 18- and 19-inch tires’ W-rating (up to 168 mph). This, however, was as close as we could get to testing the same tire in every size. We used the stock steel wheels for the 15-inch test and went to the aftermarket for the larger wheels, as most owners would do. The aftermarket wheel we chose was a cast-aluminum ASA GT1, which is available in 16- to 19-inch sizes on the Golf. It’s obvious from the test that as wheels and tires grow in size, they also grow in weight. Here’s how the test shook out:What’s immediately apparent from the results is that as the wheel-and-tire packages get larger and heavier, acceleration and fuel economy suffer. Neither is a huge surprise, but we measured a 10-percent drop in fuel economy and a four-percent degradation in 0-to-60-mph acceleration from the 15s to the 19s, which is worth considering should you be thinking about “going big.” Increasing wheel diameter and width, in turn, requires wider tires with shorter and stiffer sidewalls, which we found will increase skidpad grip, but as our test shows, there is a limit to this assertion. The 19-inch package came with the widest tires (235/35R-19) mounted to the widest wheels (8.5 inches), but this setup had less grip around the skidpad than the narrower 225/40R-18s on 8.0-inch-wide wheels. We asked the folks at Goodyear why that might be, and they postulated that the added width may have given the outside tire more grip, which would increase body roll and could therefore decrease the load on the inside tire enough to lose 0.01 g on the skidpad.
https://www.caranddriver.com/features/effects-of-upsized-wheels-and-tires-tested
After that, a drive along the expressway with occasional incline had me hovering around 27-29 mpg at 60mph for five minutes. Some coasting along the way. Surely more level land would produce more reliable results.
Regardless, driving felt better but I can still see that gas gauge dropping more than it should.
If it's not the tires/wheels (or air pressure) then it could very well be the huge pothole I'd hit prior to discovering the bubbles in my wheels...which in turn brought me down this road of wheel/tire replacements.
Will be taking the car in somewhere soon.
Sooo, as a follow up. Situation's turned into a two fold problem.
Tires:
Thinking back I recall how my tire sets came to me at around 30psi. Tire direct told me today that they were sent out at 33psi.
Here I was yesterday and they'd gone back down to around 30psi again after a week. No idea when that might've taken place. But I'd reset them 33 yesterday and this morning they were down to 30.5 to 31.5
Of course the temps dropped considerably since then.
So that's one problem.
Fuel:
I also realized how my fuel economy may've been suffering since prior to getting these tires. So that's another issue. All likely due to the pothole I'd hit.
Anyhow, FUN, FUN, FUN!
Tires:
Thinking back I recall how my tire sets came to me at around 30psi. Tire direct told me today that they were sent out at 33psi.
Here I was yesterday and they'd gone back down to around 30psi again after a week. No idea when that might've taken place. But I'd reset them 33 yesterday and this morning they were down to 30.5 to 31.5
Of course the temps dropped considerably since then.
So that's one problem.
Fuel:
I also realized how my fuel economy may've been suffering since prior to getting these tires. So that's another issue. All likely due to the pothole I'd hit.
Anyhow, FUN, FUN, FUN!
You may have an air thief in your neighborhood.
Thought HAS crossed my mind, but time will tell.You may have an air thief in your neighborhood.
I did mention how they came a few pounds short of where they should've been.
EVery 10 degree temperature change is worth about one PSI in your tires. Temp drops 30 degrees, tires go down 3 PSI.
It also could be your new tires have a higher coefficient of friction than the old ones had. CR and I believe TR rank tires on this trait too.
It also could be your new tires have a higher coefficient of friction than the old ones had. CR and I believe TR rank tires on this trait too.
Or DT may have put the wrong air in each tire, maybe there's rear air in the front tires. Might want to rotate the air. A friend suggested that.You may have an air thief in your neighborhood.
It is possible that the valves are dirty and you're losing some air through the stems. It's unlikely but possible. Make sure your caps are clean and tight as well.
Interesting articleOur test employed nearly identical Goodyear Eagle GT ultra-high-performance all-season tires in all five sizes...
Effects of Upsized Wheels and Tires Tested
Shorter tires equal gear reduction. Taller tires equal higher gear drive.
Taller tires equal less tire revolution per mile, Shorter tires equal more tire revolution per mile.
With shorter tires you have a gear reduction which means the engine is working harder. That's why you are getting worse gas mileage.
Taller tires equal less tire revolution per mile, Shorter tires equal more tire revolution per mile.
With shorter tires you have a gear reduction which means the engine is working harder. That's why you are getting worse gas mileage.
1 - 19 of 19 Posts
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