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Do you agree that the 245 would fit in the front, based on what I posted above?
And yes, I might consider an entire winter wheel / tire package. But seeing I just got this less than a week ago, that is at least 6 months out of my mind. Oh wait, did I say out of my mind? lol
Seeing that I don't want to downsize the rear tires, I think my preference would be to get 245 in the front, if they would fit. Seeing that my current tires are 25.5" diameter / 9.3" wide, a 26.7" diameter / 9.6" wide tire should fit:
What do you guys think?
As well, I can get Ultra High Performance All-Season tires in that size at a reasonable cost, eliminating the need to swap tires / rims in the winter.
Thoughts?
(this is exhausting)
My opinion on swapping tires is effectively covered above. You need to be sure the rim dimensions are compatible with the tire sizes you are quoting. Do you know rim width of both front and rear? They may not be the same as what came with the OE 18" package. For example, an 8" rim will fit a 235 better than a 245 section. While a 9" rim would be more accommodating a 245. You've got a 295 tire on the rear, so I will assume that is an 11" wide wheel. Getting the specs are important.
Originally Posted by Porschetech3
The C4s and Turbo have a viscous clutch that applies torque to the front wheels whenever there is a difference in back-front wheel speed. The more the speed difference, the more the clutch applies, you will destroy the viscous clutch with your present set-up , let alone ill handling and dangerous..
I was going to expand on the viscous diff. This is a big problem; let's hope it's not too late.
Do you agree that the 245 would fit in the front, based on what I posted above?
And yes, I might consider an entire winter wheel / tire package. But seeing I just got this less than a week ago, that is at least 6 months out of my mind. Oh wait, did I say out of my mind? lol
I should retract this [[[I measured with a ruler and it is right around 9". Since the existing tires are 9.3, I figured a 9.6 (for the 245) shouldn't be a problem. And the rims extend beyond the tires (outwards), if that says anything.]]]
I suppose the only real way is to have the tire removed and the thing measured?
When I got it, I drive a few miles and heard a high pitched noise coming from the front. It didn't seem like it was speed related. It went away when I turned right and it hasn't come back since. Is that what I could expect from the viscous thing?
Luckily these tires look almost brand new. Perhaps the owner just put them on with the larger wheels.
I measured with a ruler and it is right around 9". Since the existing tires are 9.3, I figured a 9.6 (for the 245) shouldn't be a problem. And the rims extend beyond the tires (outwards), if that says anything.
When I got it, I drive a few miles and heard a high pitched noise coming from the front. It didn't seem like it was speed related. It went away when I turned right and it hasn't come back since. Is that what I could expect from the viscous thing?
Luckily these tires look almost brand new. Perhaps the owner just put them on with the larger wheels.
Rim width is measured on the inside of the bead. You could easily assume you have a 9" wheel if you are not aware of this. See below:
If you are not sure if you measured correctly, there should be stampings or cast-in dimensions on the inside of the wheels. You will want to be sure of this. Guessing and rushing into an uniformed purchase is not a good plan. Didn't you already question, WHO DOES THIS?
I can't answer the question about the noise. I am not knowledgeable enough on Porsche's system to offer an opinion. But it's not out of the question that the viscous diff was objecting to what it was being asked to do.
Rim width is measured on the inside of the bead. You could easily assume you have a 9" wheel if you are not aware of this. See below:
If you are not sure if you measured correctly, there should be stampings or cast-in dimensions on the inside of the wheels. You will want to be sure of this. Guessing and rushing into an uniformed purchase is not a good plan. Didn't you already question, WHO DOES THIS?
I can't answer the question about the noise. I am not knowledgeable enough on Porsche's system to offer an opinion. But it's not out of the question that the viscous diff was objecting to what it was being asked to do.
I'll have one tire removed tomorrow so I can measure.
On a positive note (maybe), I did see that the front struts were replaced with Bilstein B6 Performance units.
Rim width is measured on the inside of the bead. You could easily assume you have a 9" wheel if you are not aware of this. See below:
If you are not sure if you measured correctly, there should be stampings or cast-in dimensions on the inside of the wheels. You will want to be sure of this. Guessing and rushing into an uniformed purchase is not a good plan. Didn't you already question, WHO DOES THIS?
I can't answer the question about the noise. I am not knowledgeable enough on Porsche's system to offer an opinion. But it's not out of the question that the viscous diff was objecting to what it was being asked to do.
Before I have the tire removed, do you think the size would be visible by just removing the wheel from the car (with full access)? Or is the size generally cast inside, requiring tire removal?
Not really any need to remove a tire. Porsche wheels have the “J” contour beadseat as shown here in the center sketch.
You can get reasonably close to the dimension inside the beadseat by measuring the overall width of the outside and subtracting 2 x 11mm= 0.866”.
I used an inspection camera and all I could see on the inside of the wheels was "R46 A980". I couldn't see much else. I'll have a tire removed tomorrow as they are probably not porsche wheels.
The brand or manufacturer of the wheels don’t matter, the bead seat area Dimensions are an industry standard that both wheel and tire manufacturers adhere to, so that tires interface properly with wheels.
The brand or manufacturer of the wheels don’t matter, the bead seat area Dimensions are an industry standard that both wheel and tire manufacturers adhere to, so that tires interface properly with wheels.
So you are saying I could use Scott's picture above (for example), measure the outside to outside distance and subtract 22?
Just remove a wheel from the car. Look inside the wheel - you do not need to remove the tire. There will be a lot of information in there. The rim width, wheel diameter and offset should all be there. Wheel manufacturers are required to put this information on all wheels.
The important stuff is in the first few seconds of the video:
Just remove a wheel from the car. Look inside the wheel - you do not need to remove the tire. There will be a lot of information in there. The rim width, wheel diameter and offset should all be there. Wheel manufacturers are required to put this information on all wheels.
Yes - 19 x 8 with 46 mm offset (and J is the bead profile as previously pointed out). I'll have to see if I can find a Tire & Rim Association Yearbook (it is the bible for wheel and tire engineers). The interwebz are pretty good at this stuff too.
Can you do the same at the rear? Also, please confirm you have a 295/35 tire. I saw a few inconsistencies between your numbers and what Charlie posted for the original 18" fitment.
Looks like 245 might be a good fit on an 8" wide wheel. I'll get back with a recommended aspect ratio when I know, for sure, the size of the rear tire.
Yes - 19 x 8 with 46 mm offset (and J is the bead profile as previously pointed out). I'll have to see if I can find a Tire & Rim Association Yearbook (it is the bible for wheel and tire engineers). The interwebz are pretty good at this stuff too.
Can you do the same at the rear? Also, please confirm you have a 295/35 tire. I saw a few inconsistencies between your numbers and what Charlie posted for the original 18" fitment.
This chart is what I found as far as the tires go. It does not specify the wheel width:
As I mentioned, I would like to go with the 245 / 40 / 19. It looks like it should fit fine .. if you could give me your 0.02.
03-26-2019, 08:52 PM
