Understanding offset, lowering and wheels/tire size
#1
Understanding offset, lowering and wheels/tire size
So I understand that if you have too negative an offset then you run up against the possibility of rubbing when you lower your car. I got the hotchkis springs/trd struts on with 17" wheels that have a +35 offset and get the occasional rubbing some others have commented on within the forums.
I was throwing numbers in at carbibles.com checking out measurements of different sizes, specifically focusing on where the outside edge of the tire will be in relation to the fender. So here's some numbers (posted as tire width and offset):
225 +35 puts the outside edge of the tire 15mm further out than stock
225 +45 puts the ouside edge of the tire 5mm further out than stock.
235 +45 puts the outside edge of the tire 10mm further out than stock.
245 +45 puts the outside edge of the tire 15mm further out than stock.
Now, if I go all the way to 245 tires on +45 offset I'm gonna be back to the same situation as I'm in now because the outer edge of my tire is going to be at the same place, right? Or is that not the case and I'm reasoning wrong.
I'm running 225 +35, so if I go to a wheel that is +45mm offset I bring the outer edge in by 10mm, which really isn't a whole lot. Is that really enough to fix the occasional rubbing? Does the width of the wheel make a difference, like if I go from 7" to 7.5" or even 8.0" width? What if I go from 17" to 18" wheels?
I know there are some guys out there running 245mm width tires on 18's with their cars lowered at least as much as the hotchkis lower the car, but they are claiming no issues at all with the +45mm offset.
So how does the whole "does it rub" deal work? Will getting a wheel with the stock offset (+45) really fix the issue even I get a 245 tire?
Thanks,
-K
I was throwing numbers in at carbibles.com checking out measurements of different sizes, specifically focusing on where the outside edge of the tire will be in relation to the fender. So here's some numbers (posted as tire width and offset):
225 +35 puts the outside edge of the tire 15mm further out than stock
225 +45 puts the ouside edge of the tire 5mm further out than stock.
235 +45 puts the outside edge of the tire 10mm further out than stock.
245 +45 puts the outside edge of the tire 15mm further out than stock.
Now, if I go all the way to 245 tires on +45 offset I'm gonna be back to the same situation as I'm in now because the outer edge of my tire is going to be at the same place, right? Or is that not the case and I'm reasoning wrong.
I'm running 225 +35, so if I go to a wheel that is +45mm offset I bring the outer edge in by 10mm, which really isn't a whole lot. Is that really enough to fix the occasional rubbing? Does the width of the wheel make a difference, like if I go from 7" to 7.5" or even 8.0" width? What if I go from 17" to 18" wheels?
I know there are some guys out there running 245mm width tires on 18's with their cars lowered at least as much as the hotchkis lower the car, but they are claiming no issues at all with the +45mm offset.
So how does the whole "does it rub" deal work? Will getting a wheel with the stock offset (+45) really fix the issue even I get a 245 tire?
Thanks,
-K
#6
235 +35 would have the outer edge of the tire around 20mm further out than stock, switching to a +45 offset would pull it in by 10mm.
So I know that at my current settings I am 15mm out and I'm getting occasional rubbing. If I reduce it by at least 5mm so I'm 10mm out the rubbing issue is resolved?
Also, if I understand correctly reducing the distance can be done by either using a narrower tire or by increasing the offset.
So here's my follow up question: using the width of the wheel well, from the inner edge to the fender liner, there must be a way to calculate maximum allowable tire width and offset combination, right? Would the rolling radius (unloaded) come into play there?
-K
So I know that at my current settings I am 15mm out and I'm getting occasional rubbing. If I reduce it by at least 5mm so I'm 10mm out the rubbing issue is resolved?
Also, if I understand correctly reducing the distance can be done by either using a narrower tire or by increasing the offset.
So here's my follow up question: using the width of the wheel well, from the inner edge to the fender liner, there must be a way to calculate maximum allowable tire width and offset combination, right? Would the rolling radius (unloaded) come into play there?
-K
#8
First of all, the trd shocks will not bring the front down any more then the hothckis have them. In fact, since they are stiffer, you should actually see LESS rubbing over bumps, since it does not bounce as much.
That being said, I have Hotchkis springs and Koni shocks.
I was running 18x8.5 with a 35 offset wrapped in 225/40/18 tires. I rubbed like CRAZY! Over even teh slightes dip at speed. Freeway was fine. However, I was rugbbing on in plastic lining on the wheel well,not the fender.
Stay with a 40-45 offset and you should be able to do 225s on an 18x8 just fine. If you want to go to a 235, you will have to get a 45 offset, and you might still be pushing it, at least with the hotchkis drop.
I know what the numbers say, but actually looking at the drop, I dont' think there are many springs that drop the front lower then the Hothckis. Goldlines, maybe. But the S.Tech say they drop, what, 2.5 up front? And they look the same as hotchkis IMO.
That being said, I have Hotchkis springs and Koni shocks.
I was running 18x8.5 with a 35 offset wrapped in 225/40/18 tires. I rubbed like CRAZY! Over even teh slightes dip at speed. Freeway was fine. However, I was rugbbing on in plastic lining on the wheel well,not the fender.
Stay with a 40-45 offset and you should be able to do 225s on an 18x8 just fine. If you want to go to a 235, you will have to get a 45 offset, and you might still be pushing it, at least with the hotchkis drop.
I know what the numbers say, but actually looking at the drop, I dont' think there are many springs that drop the front lower then the Hothckis. Goldlines, maybe. But the S.Tech say they drop, what, 2.5 up front? And they look the same as hotchkis IMO.
#10
Originally Posted by mattieg
Anyone have H&R coilovers with rims?
#16
i'm on hotchkis springs and have a set of enkei 17x7 +35 offset wheels on, and 225/45 sumitomos and they do rub a bit. Knowing that I drive in downtown Los Angels frequently, and that the caltrans gave up trying to improve the streets there, I rub about 3-4 times a day, mostly the front driver side tire. But, theres no problem when turning, just when there's a ugly ditch in the middle of the road when i'm not paying attention.
#17
Senior Member
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Scion Evolution
Join Date: Sep 2007
Location: San Diego (4s king)
Posts: 2,657
to the OP, the way you're listing things is rather awkward...
would probably make more sense to list rim diameter and offset together and tire specs together because these all come into play when talking figuring out if you're gonna be rubbing or not
ie: stock rims and tires
17x7 +45 with 225/45/17
would probably make more sense to list rim diameter and offset together and tire specs together because these all come into play when talking figuring out if you're gonna be rubbing or not
ie: stock rims and tires
17x7 +45 with 225/45/17
#18
Originally Posted by Aroddalobster
i'm on hotchkis springs and have a set of enkei 17x7 +35 offset wheels on, and 225/45 sumitomos and they do rub a bit. Knowing that I drive in downtown Los Angels frequently, and that the caltrans gave up trying to improve the streets there, I rub about 3-4 times a day, mostly the front driver side tire. But, theres no problem when turning, just when there's a ugly ditch in the middle of the road when i'm not paying attention.