The definitive, end-all, master FD wheel fitment guide
12-21-05, 11:58 PM
#1
The definitive, end-all, master FD wheel fitment guide
Don't you owners think it's time that we all chip in a little effort and establish a nice "real world" wheel fitment guide that members can bank on. I know there are a couple spread sheets out there and several members who are quite knowledgeable in this area but a grey area still exists none the less. Once you throw in variables like flares, aftermarket trailing arms, thicker rotors, fender rolling etc. it becomes more difficult to identify an ideal offset. My recommendation is to set up a standardized method of measuring clearances so that we can put together a nice little database that everyone can use with confidence.
The method I have in mind for the rear:
1) crawl under the car while the wheels are on and mark the point where the wheel comes closest to the trailing arm with a small piece of masking tape. Draw an arrow on the tape for more precision.
2) measure the distance from the mark on the tape to the back wall of the tire and record your measurement.
3) record the distance from the front widest part of the tire to your fender lip and be sure to note whether it is rolled or not. Record your measurement.
4) Using a T-square and a straight edge, measure the true width of your tire at its widest points.
5) Now measure the backspacing by sticking a ruler flushly perpindicular to the mounting surface of the rim and a straight edge accross the top as an indicator measure the distance to the most rear point of the tire.
6) By this point you should have all the measurements you'll need to figure out the true front/backsacing capacity of your FD with your particular configuration.
7) To figure out max overall backspacing capacity add your [(trailing arm)- to- (back of tire)] measurement to the [(back of tire)- to- (mounting point)] measurement.
8) For Frontspacing capacity subtract [(back of tire)- to- (mounting point)] measurement from [true width of tire] then add [(tire-to-fender lip)]
Once these clearances are posted people should be able to figure out their wheel options by going to this sight: http://www.wheelsmaster.com/rt_specs.jsp and punch in tire offset combinations until the front/back spacing figures are less than the max clearances allowed per our spreadsheet. Be sure add a couple mms and go by the manufacturers tire widths, not the calculated tire widths.
Why not just take off the tire and measure from your rotor?... Because in order to get true measurements I think the corner being measured should be under weight, not stretched out and dangling above a jackstand.
My car is at the paint shop but I will be happy to provide measurements with RE arms, rolled fenders and 17" wheels. If several owners wouldn't mind posting real world measurements (not theoretical calculations) with pics of their rear clearances we can create a master spreadsheet to post once and for all as the definitive reference for spacing allowed with various trailing arm, suspension,wheel, tire, fender, flare combinations. It'll only work if a few people are willing to take the time to take the measurements for all to share.
-Rob
your thoughts?
The method I have in mind for the rear:
1) crawl under the car while the wheels are on and mark the point where the wheel comes closest to the trailing arm with a small piece of masking tape. Draw an arrow on the tape for more precision.
2) measure the distance from the mark on the tape to the back wall of the tire and record your measurement.
3) record the distance from the front widest part of the tire to your fender lip and be sure to note whether it is rolled or not. Record your measurement.
4) Using a T-square and a straight edge, measure the true width of your tire at its widest points.
5) Now measure the backspacing by sticking a ruler flushly perpindicular to the mounting surface of the rim and a straight edge accross the top as an indicator measure the distance to the most rear point of the tire.
6) By this point you should have all the measurements you'll need to figure out the true front/backsacing capacity of your FD with your particular configuration.
7) To figure out max overall backspacing capacity add your [(trailing arm)- to- (back of tire)] measurement to the [(back of tire)- to- (mounting point)] measurement.
8) For Frontspacing capacity subtract [(back of tire)- to- (mounting point)] measurement from [true width of tire] then add [(tire-to-fender lip)]
Once these clearances are posted people should be able to figure out their wheel options by going to this sight: http://www.wheelsmaster.com/rt_specs.jsp and punch in tire offset combinations until the front/back spacing figures are less than the max clearances allowed per our spreadsheet. Be sure add a couple mms and go by the manufacturers tire widths, not the calculated tire widths.
Why not just take off the tire and measure from your rotor?... Because in order to get true measurements I think the corner being measured should be under weight, not stretched out and dangling above a jackstand.
My car is at the paint shop but I will be happy to provide measurements with RE arms, rolled fenders and 17" wheels. If several owners wouldn't mind posting real world measurements (not theoretical calculations) with pics of their rear clearances we can create a master spreadsheet to post once and for all as the definitive reference for spacing allowed with various trailing arm, suspension,wheel, tire, fender, flare combinations. It'll only work if a few people are willing to take the time to take the measurements for all to share.
-Rob
your thoughts?
12-22-05, 10:38 AM
#3
I appreciate your effort, but everybody should be able to use Jimlab's excel sheet to answer 99% of their questions about wheel fitment... There are a few general rules everyone should know when trying to find wheels for their FD and they are:
(1) Stay as close to a +50 offset as possible
(2) Switch to aftermarket coilovers to allow as much clearance as possible
(3) try to stay as close to a 24.5" - 25" overall wheel+tire diameter as possible
When it comes to aftermarket fenders or fender rolling, then that is a custom application and can't be "standardized" like you want it to be. If you have that type of body work done on your car, then you are obviously past the point of using an excel sheet to figure out what wheels you can run. Most fender kits only add 20-30mm of space, but each fender is different, so it's impossible to say for sure what will and won't fit.
Here is a link to Jimlab's excel sheet:
https://www.rx7club.com/forum/showth...=wheel+fitment
(1) Stay as close to a +50 offset as possible
(2) Switch to aftermarket coilovers to allow as much clearance as possible
(3) try to stay as close to a 24.5" - 25" overall wheel+tire diameter as possible
When it comes to aftermarket fenders or fender rolling, then that is a custom application and can't be "standardized" like you want it to be. If you have that type of body work done on your car, then you are obviously past the point of using an excel sheet to figure out what wheels you can run. Most fender kits only add 20-30mm of space, but each fender is different, so it's impossible to say for sure what will and won't fit.
Here is a link to Jimlab's excel sheet:
https://www.rx7club.com/forum/showth...=wheel+fitment
12-22-05, 05:24 PM
#4
I'm sorry you didn't leave your name but I'm glad you posted, it'll maybe allow me to clarify the concept here. I'm going to address your post point-by-point but I mean no dissrespect.
I am 100% with you when you say that 99% of the time the Jim Lab spreadsheet will work. What I'm addressing are the grey areas in your several rules of thumb that you have listed. If this is of no benefit to you and you see it as to much of a hassle to take some measurements than don't bother, no big deal. ambiguous advice like "yeah those RE Trailing arms will give you more room in the rear and make sure to use smaller coilovers" leaves room for interpretation.
"(1) Stay as close to a +50 offset as possible" OK so how far exactly can one deviate before they get into trouble? what if the fenders are rolled? And you need to specify which tire widths you are talking about.
"(2) Switch to aftermarket coilovers to allow as much clearance as possible" At what point exactly is this necessary?
"(3) try to stay as close to a 24.5" - 25" overall wheel+tire diameter as possible" At what point exactly will the tire begin to top out? Maybe this isn't a fair question because it depends on the suspension settings and ride height.
Please also tell me where on that sheet it indicates the backspacing increase afforded by a set of RE Trailing arms? Does anyone here know exactly how much room is gained with a 17" wheel? How about an 18" wheel?
More importantly that sheet is based on calculations based off stock spacing, it would be better to compile real-world data and see pics to boot ;o). I wouldn't doubt Mazda's engineers, but by the same token they are allowing a front/rear gap safety cushion which could be reduced if needbe.
Define custom please. Is a product such as an RE trailing arm like one of the dozens currently roaming around considered custom?
18" rims allow for greater backspacing (because of trailing arm angle) than 17" rims, but how much more?
This thread isn't really intended for people planning to run tried and tested setups, it's for people running big meats or rims with less than ideal offsets due to manufacturer availability, aquiring rims from other vehicles etc. Sometimes mms matter.
"When it comes to aftermarket fenders or fender rolling, then that is a custom application and can't be "standardized" like you want it to be. If you have that type of body work done on your car, then you are obviously past the point of using an excel sheet to figure out what wheels you can run. Most fender kits only add 20-30mm of space, but each fender is different, so it's impossible to say for sure what will and won't fit."
Your fender flare point makes sense but it's also assuming ignorance on behalf of the user. Front spacing measurements will be listed and accounted for. Anyone with any sense is going to compare their actual front spacing to the listed spacing to make an appropriate estimation.
Common sense will prevail as it always does. No matter how precise the measurements may be there will always ba veriances and differences from car to car, everyone knows this. With that being said it will also be extremely useful to have a database with measurements and pictures that will provide an unequivical tool for people to compare off of or use as a pretty damn accurate baseline.
I'll post my data and maybe a few other will as well. If not, no big deal, atleast I tried ;o)
-Rob
I am 100% with you when you say that 99% of the time the Jim Lab spreadsheet will work. What I'm addressing are the grey areas in your several rules of thumb that you have listed. If this is of no benefit to you and you see it as to much of a hassle to take some measurements than don't bother, no big deal. ambiguous advice like "yeah those RE Trailing arms will give you more room in the rear and make sure to use smaller coilovers" leaves room for interpretation.
"(1) Stay as close to a +50 offset as possible" OK so how far exactly can one deviate before they get into trouble? what if the fenders are rolled? And you need to specify which tire widths you are talking about.
"(2) Switch to aftermarket coilovers to allow as much clearance as possible" At what point exactly is this necessary?
"(3) try to stay as close to a 24.5" - 25" overall wheel+tire diameter as possible" At what point exactly will the tire begin to top out? Maybe this isn't a fair question because it depends on the suspension settings and ride height.
Please also tell me where on that sheet it indicates the backspacing increase afforded by a set of RE Trailing arms? Does anyone here know exactly how much room is gained with a 17" wheel? How about an 18" wheel?
More importantly that sheet is based on calculations based off stock spacing, it would be better to compile real-world data and see pics to boot ;o). I wouldn't doubt Mazda's engineers, but by the same token they are allowing a front/rear gap safety cushion which could be reduced if needbe.
Define custom please. Is a product such as an RE trailing arm like one of the dozens currently roaming around considered custom?
18" rims allow for greater backspacing (because of trailing arm angle) than 17" rims, but how much more?
This thread isn't really intended for people planning to run tried and tested setups, it's for people running big meats or rims with less than ideal offsets due to manufacturer availability, aquiring rims from other vehicles etc. Sometimes mms matter.
"When it comes to aftermarket fenders or fender rolling, then that is a custom application and can't be "standardized" like you want it to be. If you have that type of body work done on your car, then you are obviously past the point of using an excel sheet to figure out what wheels you can run. Most fender kits only add 20-30mm of space, but each fender is different, so it's impossible to say for sure what will and won't fit."
Your fender flare point makes sense but it's also assuming ignorance on behalf of the user. Front spacing measurements will be listed and accounted for. Anyone with any sense is going to compare their actual front spacing to the listed spacing to make an appropriate estimation.
Common sense will prevail as it always does. No matter how precise the measurements may be there will always ba veriances and differences from car to car, everyone knows this. With that being said it will also be extremely useful to have a database with measurements and pictures that will provide an unequivical tool for people to compare off of or use as a pretty damn accurate baseline.
I'll post my data and maybe a few other will as well. If not, no big deal, atleast I tried ;o)
-Rob
12-23-05, 01:53 AM
#6
One problem is that precise measurements will only apply to one car -- alignment, bolt hole slop, manufactring tolerances, bushing wear, etc. all conspire to make each car unique. And even if precise measurements did transfer, each driver/owner has unique usages and expectations. The truth is that there really is gray area here, and it cannot be entirely eliminated.
-Max
-Max
12-23-05, 07:57 AM
#7
Agreed... though there's probably less potential grey in the rear. The front will always be subject to "will it rub" questions, to which I almost always reply "yes it will in some situations no matter what you do, and you have to live with it".
However, so few people have tested the more extreme rear fitments, it's hard to get concrete parameters. I think we all know a 10" wheel will fit with any appropriate size tire you want to fit, and any offset between 42 and 50 with stock fenders and trailing arms.
We also know an 11" wheel will fit (17 or 18), but you start getting into a myriad of "ifs" like what size/brand of tire (295/30/18, 305/30/18, and 315/35/17 have all been done with varying compromises accepted), and what combo of trailing arm (and shims), and fender lip roll/removal... and how low you want to ride with how aggressive an alignment.
However, so few people have tested the more extreme rear fitments, it's hard to get concrete parameters. I think we all know a 10" wheel will fit with any appropriate size tire you want to fit, and any offset between 42 and 50 with stock fenders and trailing arms.
We also know an 11" wheel will fit (17 or 18), but you start getting into a myriad of "ifs" like what size/brand of tire (295/30/18, 305/30/18, and 315/35/17 have all been done with varying compromises accepted), and what combo of trailing arm (and shims), and fender lip roll/removal... and how low you want to ride with how aggressive an alignment.
Trending Topics
12-23-05, 05:50 PM
#8
Originally Posted by ptrhahn
Agreed... though there's probably less potential grey in the rear. The front will always be subject to "will it rub" questions, to which I almost always reply "yes it will in some situations no matter what you do, and you have to live with it".
However, so few people have tested the more extreme rear fitments, it's hard to get concrete parameters. I think we all know a 10" wheel will fit with any appropriate size tire you want to fit, and any offset between 42 and 50 with stock fenders and trailing arms.
We also know an 11" wheel will fit (17 or 18), but you start getting into a myriad of "ifs" like what size/brand of tire (295/30/18, 305/30/18, and 315/35/17 have all been done with varying compromises accepted), and what combo of trailing arm (and shims), and fender lip roll/removal... and how low you want to ride with how aggressive an alignment.
However, so few people have tested the more extreme rear fitments, it's hard to get concrete parameters. I think we all know a 10" wheel will fit with any appropriate size tire you want to fit, and any offset between 42 and 50 with stock fenders and trailing arms.
We also know an 11" wheel will fit (17 or 18), but you start getting into a myriad of "ifs" like what size/brand of tire (295/30/18, 305/30/18, and 315/35/17 have all been done with varying compromises accepted), and what combo of trailing arm (and shims), and fender lip roll/removal... and how low you want to ride with how aggressive an alignment.
Peter if you wouldn't mind taking a couple pics of your trailing arm clearance and fender clearance and take a couple measurements next time you have the wheels off your car I think that data would be valuable to this thread. If it is no hassle for you to do it at your covenience that is.
Max you should do the same if you feel like it.
I'll post my data when I get my car back.
Please also give a breakdown of your tires, arms, camber, lip etc.
thanks,
Rob
01-31-06, 11:50 PM
#9
DETH TRP
iTrader: (7)
Join Date: Mar 2004
Location: Manhattan Beach, CA
Posts: 2,544
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by ptrhahn
I think we all know a 10" wheel will fit with any appropriate size tire you want to fit, and any offset between 42 and 50 with stock fenders and trailing arms.
Whats the widest rubber I could fit under there?
*I know I might need longer studs and open ended lug nuts to get enough threads with the 1/2" spacer.
Last edited by 4CN Air; 01-31-06 at 11:53 PM.
02-01-06, 02:07 AM
#10
Lives on the Forum
Join Date: Dec 2001
Location: San Lorenzo, California
Posts: 14,716
Likes: 0
Received 8 Likes
on
8 Posts
Originally Posted by 4CN Air
so what about 17x10 rears with a 35mm offset, no coilovers but RE trailing arms. Using 1/2" spacers to make the offset 48mm.
Whats the widest rubber I could fit under there?
*I know I might need longer studs and open ended lug nuts to get enough threads with the 1/2" spacer.
Whats the widest rubber I could fit under there?
*I know I might need longer studs and open ended lug nuts to get enough threads with the 1/2" spacer.
02-01-06, 03:59 PM
#12
DETH TRP
iTrader: (7)
Join Date: Mar 2004
Location: Manhattan Beach, CA
Posts: 2,544
Likes: 0
Received 0 Likes
on
0 Posts
gotcha, I had to look at the picture again. I was thinking the problem with an offset of 35 on an FD was that the inside would hit. Sorry, not a big wheel and tire guy. Although it's time I become one, I need to put down a little more power than before, somewhere between 400-450whp. I wanted to go 10" in the back so I could throw on some big guys (like 305-315) but the more I read the more that doesn't seem like a good idea, or even necessary.
Seems more like people recommend 285's (or smaller) on 10".
What would you recommend for 18x8.5 front and 18x10 rear. I really like BFG KDW2's and would pick them up if they are an option in the sizes needed. If not maybe some MX's.
Seems more like people recommend 285's (or smaller) on 10".
What would you recommend for 18x8.5 front and 18x10 rear. I really like BFG KDW2's and would pick them up if they are an option in the sizes needed. If not maybe some MX's.
02-05-06, 12:01 AM
#13
Originally Posted by 4CN Air
gotcha, I had to look at the picture again. I was thinking the problem with an offset of 35 on an FD was that the inside would hit. Sorry, not a big wheel and tire guy. Although it's time I become one, I need to put down a little more power than before, somewhere between 400-450whp. I wanted to go 10" in the back so I could throw on some big guys (like 305-315) but the more I read the more that doesn't seem like a good idea, or even necessary.
Seems more like people recommend 285's (or smaller) on 10".
What would you recommend for 18x8.5 front and 18x10 rear. I really like BFG KDW2's and would pick them up if they are an option in the sizes needed. If not maybe some MX's.
Seems more like people recommend 285's (or smaller) on 10".
What would you recommend for 18x8.5 front and 18x10 rear. I really like BFG KDW2's and would pick them up if they are an option in the sizes needed. If not maybe some MX's.
Last edited by wanklin; 02-05-06 at 12:04 AM.
06-02-06, 06:34 PM
#15
Back to life.
I have a quick question pertaining to a wheel setup that I am currently taking measurements for. I need to how close to flush the tires can be with the fender lips. Assuming that the car is somewhere near stock ride height, will the wheels rub on the rolled rear lips when the car squats through a turn? I know that the suspension moves in an inward direction due to the shock being angled towards the car's center, but I don't know how much clearance this angle creates as the car squats.
thanks
I have a quick question pertaining to a wheel setup that I am currently taking measurements for. I need to how close to flush the tires can be with the fender lips. Assuming that the car is somewhere near stock ride height, will the wheels rub on the rolled rear lips when the car squats through a turn? I know that the suspension moves in an inward direction due to the shock being angled towards the car's center, but I don't know how much clearance this angle creates as the car squats.
thanks
06-02-06, 11:13 PM
#16
Wheels should be fitted AFTER ride height and camber is set and for me I always roll/pull before fitting wheels. Otherwise you will have sunken battleship wheels, and nothing looks worse than a nice car with sunk wheels. I can say that this forum is definatly one of the most conservative as far as wheel fitment goes, there is room to deviate greatly from most of the advice offered here. I still dont understand why many of you guys like to baloon tires too, im not saying everyone should stretch but surely a square fit would be better, if you want 275's then buy some damn 10.5+" wheels and not 9's!!
06-03-06, 12:26 AM
#17
Not that I don't appreciate your input, but I have fairly firm grasp on wheel fitting offsets etc. What I'm looking for is some input on lip clearance to help me in my front spacing guestimations. I can take all the measurement I want, but I need a baseline to work off of. Unfortunately, not a whole lot of people on the forum are running rolled lips all around so I'll probably have to just go with my best educated guess and keep the tires about 1/8"-1/4" under flush.
Thread
Thread Starter
Forum
Replies
Last Post
diabolical1
2nd Generation Specific (1986-1992)
30
01-30-16 05:50 AM
