Beating a dead horse with rims and wheels
#1
02-02-2018, 09:45 PM
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Beating a dead horse with rims and wheels
I've read many forums about this, and I'm quite certain it will work. Just looking for some head nodding.
https://www.ebay.com/itm/Helo-HE890-...oAAOSwwcRaYK6B
https://www.ebay.com/itm/5x108-to-5x...!US!-1&vxp=mtr
https://www.tires-easy.com/245-30-20...BoC2RsQAvD_BwE
20x8.5 @15 ET 245/35/20 93W with 25 ET adapters
Thoughts? They look sick right?!
https://www.ebay.com/itm/Helo-HE890-...oAAOSwwcRaYK6B
https://www.ebay.com/itm/5x108-to-5x...!US!-1&vxp=mtr
https://www.tires-easy.com/245-30-20...BoC2RsQAvD_BwE
20x8.5 @15 ET 245/35/20 93W with 25 ET adapters
Thoughts? They look sick right?!
#2
02-03-2018, 07:19 AM
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Jeremy, our cars like to have around a +50mm offset(ie, the hub face sitting out to the edge of the car in relation to the center of the rim) . In your case, the rims are starting at a +15mm offset and by adding the spacers, you are going to go to a -10mm offset. This is going to push the rims out 60mm (2.3") to the outside edge of the car over what your factory rims. This in itself is going to create a lot of issues of clearance at the top of the wheel well (will require rolling of the fender well at a minimum).
You go with a rim that has a different offset (ie, one that is near +50mm), then you should be good as the tires are going to be roughly the same diameter.
This is something else that I will tell you that if you go with that wheel/rim combination that you mention and you do the things necessary to make the wheels work for general driving, you are going to be putting a lot of stress on the wheel bearings. I have a lot of experience with this on my lifted truck. You are shifting how the center of the bearing lines up with the center of the rim if you were to draw two vertical lines (one through the bearing and one through the rim). In an ideal world, you want these two lines one on top of the other. As with anything, there is some margin there. But, the further apart these 2 lines get, the more mechanical stresses that you are going to get. If you need a demonstration of this, simply grab a gallon of milk. Now, using a single finger, pull the milk in night and tight to the last knuckle (sticking your finger in as far as it will go). Lift the milk. Pretty easy, not a lot of strain on your finger. For the second half of this, using the same finger, have the gallon of milk at the tip of your finger and lift it. Feel how that gallon of milk is trying to twist your finger sideways. The same effect is happening with your wheel bearings. Are you going to destroy your wheel bearings in 100 miles. Probably not. Are you going to shorten their life. Most definitely. By how much, that is very hard to say. Too many variables in that to give a number. But in short, the bigger the difference between the centers (bearing to rim) and the rougher the roads, the shorter the bearing life is going to be.
You go with a rim that has a different offset (ie, one that is near +50mm), then you should be good as the tires are going to be roughly the same diameter.
This is something else that I will tell you that if you go with that wheel/rim combination that you mention and you do the things necessary to make the wheels work for general driving, you are going to be putting a lot of stress on the wheel bearings. I have a lot of experience with this on my lifted truck. You are shifting how the center of the bearing lines up with the center of the rim if you were to draw two vertical lines (one through the bearing and one through the rim). In an ideal world, you want these two lines one on top of the other. As with anything, there is some margin there. But, the further apart these 2 lines get, the more mechanical stresses that you are going to get. If you need a demonstration of this, simply grab a gallon of milk. Now, using a single finger, pull the milk in night and tight to the last knuckle (sticking your finger in as far as it will go). Lift the milk. Pretty easy, not a lot of strain on your finger. For the second half of this, using the same finger, have the gallon of milk at the tip of your finger and lift it. Feel how that gallon of milk is trying to twist your finger sideways. The same effect is happening with your wheel bearings. Are you going to destroy your wheel bearings in 100 miles. Probably not. Are you going to shorten their life. Most definitely. By how much, that is very hard to say. Too many variables in that to give a number. But in short, the bigger the difference between the centers (bearing to rim) and the rougher the roads, the shorter the bearing life is going to be.
#3
02-04-2018, 07:06 PM
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I thought the spacer 1" =25mm + 15mm rim would give me 40? Guess I don't know how that works. I don't understand your explanation of the wheels bearings. The tire is like 4% bigger then stock, that would make that much of difference? Wheel bearings are about 120 for a full set, I would be down to buy them if needed.
#4
02-04-2018, 09:04 PM
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Jeremy, offset is simply a measure of the relative distance between the center of the rim and the face of the hub (where the rim gets bolted down). The X-Type likes to have +50mm of distance there. So, in other words, if you were to take a ruler and found the center of the rim (inside to outside) and drew a magical line through the whole rim and then measured from that line, you would measure 50mm (towards the outside of the rim) till you hit the back of the rim where it attaches to the car.
In your case, you are starting with a rim that only has +15mm of offset. Now, add the spacer to the back of the rim. This will push the surface that the rim mounts to the car with in an additional 25mm. So, if you draw that "magical line" again and measure between that line and where the spacer gets attached to the car, you will find that the surface is actually to the inside of the car when compared to the "magical line". This is referred to as "negative offset". In this case, you would have -10mm (+15mm of offset then subtract out 25mm for the spacer, giving you -10mm of offset).
When it comes to the bearings and how offset can affect things (specifically bearing wear), you first have to understand a little bit about bearings. Bearings ultimately come in 2 styles, radial and thrust. A radial bearing is what is on the car that allows the wheels to turn. These are great for handing a load that is perpendicular to the shaft that they are mount to (ie, the CV shaft in this case). So, in other words, they like to have a load put on them that is vertical. They do not do to well when you put a side to side load on them (ie, when you turn or corner at high speeds). You then have thrust bearings. These like to have a load put on them that is in line with the shaft (ie, side to side loading as it relates to the car). So, the general weight of the car will put damaging strain on a thrust bearing if it was used for the wheels.
Now, to understand how offset works on your car, you will need a big screw driver, a metal coat hanger, some tape, and a few pound object that you can run the coat hanger through. What you are going to do is bend the coat hanger so that you have a hook that points straight down (so you can attach the weight to it), then have it come up a little, then make a 90 degree bend with say 8 inches (20 cm) of the coat hanger sticking out. You may need to put a slight S bend in the 8 inch (20cm) portion to allow it to clear the handle of the screw driver. Now, what you are going to do is center the hook on the handle and about 4" (10 cm) down on the screw driver, tape the wire to the screw driver (where the tape is can be thought of as where the tire mounts to the car). The hook is the centerline of the rim and your hand is going to be the centerline of the bearing. Now, if you put the weight on the hook and put your hand on the handle, when you pick up the screw driver, everything should pretty much balance out and you should not have to really apply anything to keep the screw driver parallel to the ground (may take a little, bit it will be minimal). Now, undo the tape and and now slide the hook as far down the screw driver that you can take it and still tape it to the screw driver. Now, pick up the screw driver again. Feel how the screw driver now wants to twist out of your hand. Because the weight (ie, center of the rim) is not in line with your hand (the center of the bearing), it is putting a twisting motion on your hand (ie, side force to a tire). If you move the weight back towards your hand some (not all the way), you can see how this twisting becomes less. When you start talking about a 4,000 pound car and then the jarring of the wheel due to hitting pot holes or high speed turns, the side force can become very large and lead to quick failures.
Now, not to muddy the waters here, but the bearings in the car are a combination radial and thrust bearing. The bearing in the wheel is actually mounted at a slight angle. This gives it characteristics of both types of bearings. This is what allows the wheel bearing to handle normal amounts of turning forces (side load). But, the bearing is meant to handle 90% of the forces in the radial direction and 10% in the thrust direction (these are relative numbers meant to make a point). You get the offset on the car off too much, you are going to need a bearing that is going to have say a 50/50 split in the forces.
If this is still confusing you, there are some good videos on Youtube that explain what offset is and how it affects things. You then need to think about how adding the spacer is going to shift things around.
If you think that I am full of it, I will accept that. I would love to hear how the tires work on your car though. I would love to see you prove me wrong. As others here have found out, I am not perfect. I have done things to vehicles that others told me could not be done. Did it come at a cost? It sure did. Kinda like with this. Will the rim mount to the car. They sure will. Can you drive in a straight line? Yep, don't doubt that. Could you drive 1000 miles in a straight line and not have a wheel bearing fail? Pretty sure you could do that too. Drive 5,000 miles in a straight line? I think this is where you will start seeing issues. Turning? I can almost guarantee that you are going to have some serious tire rubbing going on unless you do a lot of modification. Your call.
In your case, you are starting with a rim that only has +15mm of offset. Now, add the spacer to the back of the rim. This will push the surface that the rim mounts to the car with in an additional 25mm. So, if you draw that "magical line" again and measure between that line and where the spacer gets attached to the car, you will find that the surface is actually to the inside of the car when compared to the "magical line". This is referred to as "negative offset". In this case, you would have -10mm (+15mm of offset then subtract out 25mm for the spacer, giving you -10mm of offset).
When it comes to the bearings and how offset can affect things (specifically bearing wear), you first have to understand a little bit about bearings. Bearings ultimately come in 2 styles, radial and thrust. A radial bearing is what is on the car that allows the wheels to turn. These are great for handing a load that is perpendicular to the shaft that they are mount to (ie, the CV shaft in this case). So, in other words, they like to have a load put on them that is vertical. They do not do to well when you put a side to side load on them (ie, when you turn or corner at high speeds). You then have thrust bearings. These like to have a load put on them that is in line with the shaft (ie, side to side loading as it relates to the car). So, the general weight of the car will put damaging strain on a thrust bearing if it was used for the wheels.
Now, to understand how offset works on your car, you will need a big screw driver, a metal coat hanger, some tape, and a few pound object that you can run the coat hanger through. What you are going to do is bend the coat hanger so that you have a hook that points straight down (so you can attach the weight to it), then have it come up a little, then make a 90 degree bend with say 8 inches (20 cm) of the coat hanger sticking out. You may need to put a slight S bend in the 8 inch (20cm) portion to allow it to clear the handle of the screw driver. Now, what you are going to do is center the hook on the handle and about 4" (10 cm) down on the screw driver, tape the wire to the screw driver (where the tape is can be thought of as where the tire mounts to the car). The hook is the centerline of the rim and your hand is going to be the centerline of the bearing. Now, if you put the weight on the hook and put your hand on the handle, when you pick up the screw driver, everything should pretty much balance out and you should not have to really apply anything to keep the screw driver parallel to the ground (may take a little, bit it will be minimal). Now, undo the tape and and now slide the hook as far down the screw driver that you can take it and still tape it to the screw driver. Now, pick up the screw driver again. Feel how the screw driver now wants to twist out of your hand. Because the weight (ie, center of the rim) is not in line with your hand (the center of the bearing), it is putting a twisting motion on your hand (ie, side force to a tire). If you move the weight back towards your hand some (not all the way), you can see how this twisting becomes less. When you start talking about a 4,000 pound car and then the jarring of the wheel due to hitting pot holes or high speed turns, the side force can become very large and lead to quick failures.
Now, not to muddy the waters here, but the bearings in the car are a combination radial and thrust bearing. The bearing in the wheel is actually mounted at a slight angle. This gives it characteristics of both types of bearings. This is what allows the wheel bearing to handle normal amounts of turning forces (side load). But, the bearing is meant to handle 90% of the forces in the radial direction and 10% in the thrust direction (these are relative numbers meant to make a point). You get the offset on the car off too much, you are going to need a bearing that is going to have say a 50/50 split in the forces.
If this is still confusing you, there are some good videos on Youtube that explain what offset is and how it affects things. You then need to think about how adding the spacer is going to shift things around.
If you think that I am full of it, I will accept that. I would love to hear how the tires work on your car though. I would love to see you prove me wrong. As others here have found out, I am not perfect. I have done things to vehicles that others told me could not be done. Did it come at a cost? It sure did. Kinda like with this. Will the rim mount to the car. They sure will. Can you drive in a straight line? Yep, don't doubt that. Could you drive 1000 miles in a straight line and not have a wheel bearing fail? Pretty sure you could do that too. Drive 5,000 miles in a straight line? I think this is where you will start seeing issues. Turning? I can almost guarantee that you are going to have some serious tire rubbing going on unless you do a lot of modification. Your call.
#5
02-05-2018, 09:06 PM
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I appreciate the thoughtful response. I was under the impression the x type had a 40 EF https://www.jaguarforums.com/forum/x...t-offset-3308/ If i got 1.25" space it o would bring my offset to about 47. That would be better?
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02-05-2018, 09:07 PM
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#8
02-06-2018, 04:31 PM
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Jeremy, the point that I think you are missing is that the back side of the rim (where the hub touches the rim) is already too far towards the center of the rim. No amount of spacers is going to make it better. They will only make it worse.
I am going to try explaining it a different way using a slightly different term. This term would be "backspacing". This is simply a measurement of the distance from the inside edge of the rim (a magical line running from one side of the rim to the other) to the back side of the rim where the hub touches the rim. Where this number becomes less useful is when you start changing the width of the rim as the backspacing becomes somewhat relative. What I mean by this will be explained below.
If you start with the 7" wide rims that come on the X-Type, the backspacing depth is 5.5" (3.5" to go from the back side of the rim plus another 2" for the factory offset (ie, +50mm divided by 25mm per inch). To get the proper backspacing on an 8" wide rim, you would need a rim with a backspacing of 6" (4" to get to the center of the rim, plus the 2" for the +50mm of offset).
In the case of rims that you are looking at, they are 8" wide rims with a +15mm offset. So, the backspacing on those rims would be 4.6" (4" to get to the center of the rim and 0.6" when you convert the +15mm to inches). If you were to add a 1" spacer to the back of the rim (where the hub touches the rim) and then you took a ruler and measured from the back of the rim (that magical line) to where the surface of the spacer is now, you would only get 3.6".
I am hoping that this is making a little more sense since you are dealing with only a single value (back of the rim to where the hub attaches) as compared to a relative value (center point of the rim to where the hub attaches). Some people seem to grasp backspacing easier than offset.
Any which way you look at it, what you are attempting to do is put the center of the rim in line with the center of the bearing. If you do decide to go with those rims, you would be best off to simply skip the spacer all together as that would put you closer to keeping things where they should be. The only time a spacer should be used is when you are attempting to run a rim that has a very flat face (ie, the side of the rim that you see) and has a very high offset number. Then, by adding a spacer, you bring the spot where the hub attaches to the rim more in line. In other words, picture this: You have an 8" wide rim with an offset of +75mm (the spokes of the rim are pretty much in line with the outside lip of the rim). This is too much offset for the X-type. If you were to add the spacer to this rim, you would be adding 25mm of spacer, which would effectively make the point where the hub attaches to the rim at +50mm (ie, +75mm of offset minus the 25mm for the spacer since the spacer is bringing the mounting point closer to the center of the rim).
As for what is the proper offset for the X-Type, I think this really depends on where you get your numbers from. I have looked in the service manual for the car and it says nothing about what the proper offset should be (does not reference backspacing either). I went to a rim/tire seller and put in the car and asked it to recommend rims for the car. If you do this, you will find that all of the rims that it is going to recommend will be in the +40 to +50 mm offset range. You get the offset in that range, then you are good.
I am going to try explaining it a different way using a slightly different term. This term would be "backspacing". This is simply a measurement of the distance from the inside edge of the rim (a magical line running from one side of the rim to the other) to the back side of the rim where the hub touches the rim. Where this number becomes less useful is when you start changing the width of the rim as the backspacing becomes somewhat relative. What I mean by this will be explained below.
If you start with the 7" wide rims that come on the X-Type, the backspacing depth is 5.5" (3.5" to go from the back side of the rim plus another 2" for the factory offset (ie, +50mm divided by 25mm per inch). To get the proper backspacing on an 8" wide rim, you would need a rim with a backspacing of 6" (4" to get to the center of the rim, plus the 2" for the +50mm of offset).
In the case of rims that you are looking at, they are 8" wide rims with a +15mm offset. So, the backspacing on those rims would be 4.6" (4" to get to the center of the rim and 0.6" when you convert the +15mm to inches). If you were to add a 1" spacer to the back of the rim (where the hub touches the rim) and then you took a ruler and measured from the back of the rim (that magical line) to where the surface of the spacer is now, you would only get 3.6".
I am hoping that this is making a little more sense since you are dealing with only a single value (back of the rim to where the hub attaches) as compared to a relative value (center point of the rim to where the hub attaches). Some people seem to grasp backspacing easier than offset.
Any which way you look at it, what you are attempting to do is put the center of the rim in line with the center of the bearing. If you do decide to go with those rims, you would be best off to simply skip the spacer all together as that would put you closer to keeping things where they should be. The only time a spacer should be used is when you are attempting to run a rim that has a very flat face (ie, the side of the rim that you see) and has a very high offset number. Then, by adding a spacer, you bring the spot where the hub attaches to the rim more in line. In other words, picture this: You have an 8" wide rim with an offset of +75mm (the spokes of the rim are pretty much in line with the outside lip of the rim). This is too much offset for the X-type. If you were to add the spacer to this rim, you would be adding 25mm of spacer, which would effectively make the point where the hub attaches to the rim at +50mm (ie, +75mm of offset minus the 25mm for the spacer since the spacer is bringing the mounting point closer to the center of the rim).
As for what is the proper offset for the X-Type, I think this really depends on where you get your numbers from. I have looked in the service manual for the car and it says nothing about what the proper offset should be (does not reference backspacing either). I went to a rim/tire seller and put in the car and asked it to recommend rims for the car. If you do this, you will find that all of the rims that it is going to recommend will be in the +40 to +50 mm offset range. You get the offset in that range, then you are good.
#9
02-06-2018, 06:04 PM
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#10
02-06-2018, 08:37 PM
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Yes, you can even go to an 8" wide rim (this will push the outside edge of the rim out towards the edge of the car by a 1/2" or so if that is the look you are going after). The big thing is keeping the tire diameter to roughly (+1" max) what the stock tire is. I went from the stock 225/45R17's to 235/45R17's and that was about as big as the car would take. the tires just missed the back of the wheel well and you could see where there was even very minor brushing of the tire against the fender liner under certain conditions. Nothing I was worried about damaging a tire with, but that gives you an idea of how tight things are.
But, like you said, stick with the +40-50mm offset and you will be fine.
But, like you said, stick with the +40-50mm offset and you will be fine.
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