Andyinchville1
Veteran Member
Hi All,
Been doing a lot of searching and reading but cannot seem to find good and hard answer to my questions so I figure i would ask it here (or possibly again so sorry).
I am currently running p 205 70 R 15 Ecopia 422 plus tires on my car (I did switch from the steelies than came with my car to junkyard Avus rims).
I seem to have no issue running these tires and even got a small bump in fuel economy in the driving I do (virtually unloaded , mostly highway).
It's time for new tires again and I want to up-size again .... I am keeping the same rims because I need to save some $$ too so no upsizing to 16" rims and new tires,
Anyways, I really want to get p 215 75 R 15 tires BUT that MAY be too big without lift BUT figured I'd ask if it would fit on may car given the set up I have (basically stock suspension except Koni Special Actives all around , Lesjofors VR6 springs up front, while it may not matter upgraded A arms with TT bushings and a rear sway bar).
I believe I saw some posts saying 205 75 R15 will more or less fit without issue so that i my safe fall back if I can't get definitive answers on the larger tires.
FWIW - in the larger tires I have researched I will be getting either Hankook Kinergy ST H735 or Goodyear Assurance A/S in that order ...If Ecopias were available in those sizes I would consider them buy they are not
If a tire is too big , what would hit first in my case ? (I did read about a bump in the rear liner possibly hitting the rear tire but I did not see the bump in my car (may have to look closer) and I have pretty good clearance between the tire and the lower spring perch (no missing or rubbed paint but doesn't the perch move up as the spring compresses?).
Questions other than fitment :
1) I know rotating weight matters more for city than highway BUT is there any formula how much an extra pound tire rotating weight affects MPG's on the car ?
2) I know aero plays a bigger role at highway speeds BUT how much aero MPG is lost by raising the car an additional inch or 2 ? ...
I find it hard to imagine that an inch or 2 really matters since air is getting under the car anyways ? ...
In theory isn't most of the loss from going taller usually the result of the tires (as in the case of 4x4 vehicles going with big aggressive / heavy mudders etc ?
Has anybody actually seen a difference MPGs in our Jettas just by raising the height an inch or two assuming keeping the same exact tires before and after a lift?
3) I read that filling the wheel wells (lessen the air volume) helps with MPG's ... why is that? or is it a false notion since filling the wheel wells with a taller tire getting better fuel economy just by changing the effective gearing and has nothing to do with airspace?
I'm hoping to order tires next week sometime after some sizing feedback / research .... I did PM a few folks too.
Thanks in advance for any and all help.
Andrew
Been doing a lot of searching and reading but cannot seem to find good and hard answer to my questions so I figure i would ask it here (or possibly again so sorry).
I am currently running p 205 70 R 15 Ecopia 422 plus tires on my car (I did switch from the steelies than came with my car to junkyard Avus rims).
I seem to have no issue running these tires and even got a small bump in fuel economy in the driving I do (virtually unloaded , mostly highway).
It's time for new tires again and I want to up-size again .... I am keeping the same rims because I need to save some $$ too so no upsizing to 16" rims and new tires,
Anyways, I really want to get p 215 75 R 15 tires BUT that MAY be too big without lift BUT figured I'd ask if it would fit on may car given the set up I have (basically stock suspension except Koni Special Actives all around , Lesjofors VR6 springs up front, while it may not matter upgraded A arms with TT bushings and a rear sway bar).
I believe I saw some posts saying 205 75 R15 will more or less fit without issue so that i my safe fall back if I can't get definitive answers on the larger tires.
FWIW - in the larger tires I have researched I will be getting either Hankook Kinergy ST H735 or Goodyear Assurance A/S in that order ...If Ecopias were available in those sizes I would consider them buy they are not
If a tire is too big , what would hit first in my case ? (I did read about a bump in the rear liner possibly hitting the rear tire but I did not see the bump in my car (may have to look closer) and I have pretty good clearance between the tire and the lower spring perch (no missing or rubbed paint but doesn't the perch move up as the spring compresses?).
Questions other than fitment :
1) I know rotating weight matters more for city than highway BUT is there any formula how much an extra pound tire rotating weight affects MPG's on the car ?
2) I know aero plays a bigger role at highway speeds BUT how much aero MPG is lost by raising the car an additional inch or 2 ? ...
I find it hard to imagine that an inch or 2 really matters since air is getting under the car anyways ? ...
In theory isn't most of the loss from going taller usually the result of the tires (as in the case of 4x4 vehicles going with big aggressive / heavy mudders etc ?
Has anybody actually seen a difference MPGs in our Jettas just by raising the height an inch or two assuming keeping the same exact tires before and after a lift?
3) I read that filling the wheel wells (lessen the air volume) helps with MPG's ... why is that? or is it a false notion since filling the wheel wells with a taller tire getting better fuel economy just by changing the effective gearing and has nothing to do with airspace?
I'm hoping to order tires next week sometime after some sizing feedback / research .... I did PM a few folks too.
Thanks in advance for any and all help.
Andrew
