The Official Wide Tire Thread
Nov 26, 2014, 10:11 AM
#632
EvoM Guru
iTrader: (1)
I don't know, I've never looked at the SAI all that close on my car to determine what acceptable offset is. Especially since I haven't began pondering building my suspension, yet. On most cars, you want to stay close to the OEM offset, which I have done, my wheels are +35. Stock offset is
+38. His effective offsets with those spacers will be in the -15 range, which would probably be far from ideal. For a show car, it doesn't matter.
You do want some scrub radius, it generates road feel and has some other benefits that are hard to explain. But the more you have, the more the contact patch of the tire moves (as opposed to simply rotating) and changes the wheel base as you turn the steering wheel because the tire is moving fore and aft as you turn the steering wheel, not just rotating.
On my offroad car, when I built the suspension, I gave it 3/4" of scrub radius with a 35x12.50 tire and 0 offset wheel. With the geometry it has (roll center, camber gain, caster, SAI, etc), I feel it handles better than a lot of road cars.
+38. His effective offsets with those spacers will be in the -15 range, which would probably be far from ideal. For a show car, it doesn't matter.
You do want some scrub radius, it generates road feel and has some other benefits that are hard to explain. But the more you have, the more the contact patch of the tire moves (as opposed to simply rotating) and changes the wheel base as you turn the steering wheel because the tire is moving fore and aft as you turn the steering wheel, not just rotating.
On my offroad car, when I built the suspension, I gave it 3/4" of scrub radius with a 35x12.50 tire and 0 offset wheel. With the geometry it has (roll center, camber gain, caster, SAI, etc), I feel it handles better than a lot of road cars.
Nov 26, 2014, 03:24 PM
#633
The scrub radius is also affected by the kingpin angle which on our MacPherson strut cars are affected by camber. For the same offset you will dial out scrub radius as you dial in camber. So on cars with a lot of camber running lower offset actually preserves scrub radius.
High scrub radius gives you better road feedback as said above but will increase tramling. Low scrub radius will decrease road feel but also decrease tramlining. In very simplistic terms. In reality you juggle kingpin angle with caster and offset. (If you were that dedicated to suspension work)
High scrub radius gives you better road feedback as said above but will increase tramling. Low scrub radius will decrease road feel but also decrease tramlining. In very simplistic terms. In reality you juggle kingpin angle with caster and offset. (If you were that dedicated to suspension work)
Nov 28, 2014, 06:12 PM
#634
I have a few 18x10 questions, stock body evo 8 ......+15,+25 or +35 ... im trying not to run a spacer up front to but i will, the rear fit good with +25??? i need help asap so i can order my wheels
Dec 1, 2014, 10:47 AM
#638
EvoM Guru
iTrader: (1)
The scrub radius is also affected by the kingpin angle which on our MacPherson strut cars are affected by camber. For the same offset you will dial out scrub radius as you dial in camber. So on cars with a lot of camber running lower offset actually preserves scrub radius.
High scrub radius gives you better road feedback as said above but will increase tramling. Low scrub radius will decrease road feel but also decrease tramlining. In very simplistic terms. In reality you juggle kingpin angle with caster and offset. (If you were that dedicated to suspension work)
High scrub radius gives you better road feedback as said above but will increase tramling. Low scrub radius will decrease road feel but also decrease tramlining. In very simplistic terms. In reality you juggle kingpin angle with caster and offset. (If you were that dedicated to suspension work)
Camber does not change scrub radius since the tire moves with the SAI. What does effect SAI is the concentric adjustment bolt at the top of the spindle. Adjusting camber with camber plates does not change scrub radius.
Dec 1, 2014, 11:27 AM
#640
^Lol so true...its pretty obvious based on the question asked if the person has actually spent any time reading before posing the question.
How many times does it need to be stated that the rear likes a high offset and the front likes a low offset so when going wide a spacer in the front is almost always needed!?
How many times does it need to be stated that the rear likes a high offset and the front likes a low offset so when going wide a spacer in the front is almost always needed!?
Dec 1, 2014, 11:58 AM
#641
It's quite sad actually. First there are the guys who do the leg work to get parts fit up properly. Then there are the guys who read it, and say hey look what I did, and basically copies what the previous guy did. Now we have the guy who wants it spoon fed to him without any legwork whatsoever. I've spent quite a few years on this forum reading every thing and anything that is technical and I'm not done. I wish people would just perform their due diligence, and not slow the process of those who are genuinely interested in moving forward.
Dec 1, 2014, 01:08 PM
#642
Well unfortunately that is just part of life and you will run into it whether you are in school in the office and even on car forums. I specifically recall working on a group project back in college (not too long ago I'm pretty young) where half my group members were essentially non-existent so we were forced to do twice the amount of work to make up for their lack of assistance. It sucked but was quite satisfying when we got to tare them a new one on their evaluation.
There are a lot of lazy people who will do the bare minimum just to get by and then there are those who truly care, put forth the effort and want to help others so they document their work and answer questions. That is what is generally great about this forum and why I do my best to give back and help those when I can.
There are a lot of lazy people who will do the bare minimum just to get by and then there are those who truly care, put forth the effort and want to help others so they document their work and answer questions. That is what is generally great about this forum and why I do my best to give back and help those when I can.
Dec 1, 2014, 03:31 PM
#643
It's quite sad actually. First there are the guys who do the leg work to get parts fit up properly. Then there are the guys who read it, and say hey look what I did, and basically copies what the previous guy did. Now we have the guy who wants it spoon fed to him without any legwork whatsoever. I've spent quite a few years on this forum reading every thing and anything that is technical and I'm not done. I wish people would just perform their due diligence, and not slow the process of those who are genuinely interested in moving forward.
true. but then a lot of us do the work so that people not in the know can learn from what we've done and not have to make mistakes, etc. i don't mind reiterating info to help someone out.
Dec 1, 2014, 03:57 PM
#644
Well actually everyone is telling me different, and I'm trying to make 100% sure before I order these rims because I can not return them, I have fit a 18x10 +37 in the rear and was sunk in, so I'm trying to get all my ducks in a row, and actually I have read just about everything page on the wide tire, offset etc etc pages...and have also seen people doing the same setup...but thank you for the help guys 👍
Dec 1, 2014, 04:34 PM
#645
It wasn't to single you out 03BBY1088, it just runs rampant. I can appreciate doing the research on the wheels before buying, but some just lob one up. I think that size will work just fine in my opinion. Spacers and a few other things that you've read already will be key.