tire size opinions (15")

sizes

  • 205/50 all around

    Votes: 0 0.0%
  • 205/50 in front 225/45 in the rear (Hussein is using this combo if I remember the dallara thread)

    Votes: 0 0.0%
  • 205/50 front 245/40 in the rear

    Votes: 1 33.3%
  • 225/45 front 245/40 rear

    Votes: 1 33.3%
  • strength training, and rework the entire front suspension and 245/40 all around. (sarcasm)

    Votes: 1 33.3%

  • Total voters
    3

autox19

True Classic
so I have 15x8 0 offset wheels on the way. now for the tires. First, I plan on putting on flares (from midwest, either Brayens choice or full faza)
so here we go.

Odie
 
Your car is basically stock in terms of the body so looking at Hussein’s car for guidance on what to apply to your car is not a good idea.

I have some likely bad news, they are going to be a difficult rim to use on your car as it exists now.

Using this site http://www.rimsntires.com/specspro.jsp

Gives us the following information

C175286F-32A3-4F31-A1F1-6B780C01346D.jpeg
C10F8B7E-64F5-45E6-911E-AC0904168F84.jpeg



You will likely have significant problems in front and less of a problem in back but will likely find the fender lips will bottom on the top of the tire as it will stick out well beyond the fender lip.

Try playing with the calculator to find what you can do in regards to tire width and aspect ratio.

Any chance you can return the rims?
 
A more easily dealt with arrangement would be a 7.0” rim with 20-27mm of positive offset and a 185-195/45 tire.
 
Notice the part that said I am going to use flares. So I don't plan on keeping them tucked under the stock fenders

Odie
 
I also went to 15" wheels but wanted to keep the stock body so after all my calculations I came up with 15x7 with 195/45 tires and a 15 ET.

Although I haven't as yet driven my '74 X with this set up I can say that the front tires touch the inner wheel well (no liners) on the interior side at full lock. The drives side tire also comes fairly close to the lower front fender lip but I'm hoping the alignment takes care of that.

The key is of course the offset.
 
Personally I installed Fiat 500 Rims (15") with 195/45 R15 S Drive tires. A 1" spacer is required. Slight rubbing at each lock on the fender liner. Fixed that problem by adding a few teck screws. Rims for a set of 4 was only $350 from LKQ auto wreckers.

TonyK.

Grimsby Ontario Canada.
 
Virtually any combination is possible if you are going to extend the wheels arches/fenders and use spacers. Over here if the car is used in competition you can't have a spacer bigger than 1" or 25mm for safety reasons and so I would say suggest that's a good guideline to go by. To reduce the size of spacer and/or offset to the minimum you would benefit from going from the standard springs to 2.25" diameter springs, commonly found on competition suspension. The bigger the offset and spacer the more it can upset the front steering geometry and causes fouling of the inner wheel arches/bodywork. Adjustable suspension top mounts can address some of the above. When fitting the Abarth body kit on my car I was surprised at how much of the front arches I had to cut away to allow full lock to be applied. I run 13" 205's all round with 1" spacers, but the spacer is more to move the wheel out to fill the arches.
 
Thought I might have to go with a coil over kit. I am waiting for the wheels to physically be here before I go that route. This car will probably never see a track or auto-x as the last one in Lansing was about 25 years ago. Going more for look and fun back road driving.

Odie
 
Gotta love it. Like others on this forum, I've been involved in the VW scene. If this conversation took place on the VW forum it would be full of words like: "poke", "stretch", "stance", "flush", "hella flush", "lip", etc, etc. But not here, thank God.
 
Gotta love it. Like others on this forum, I've been involved in the VW scene. If this conversation took place on the VW forum it would be full of words like: "poke", "stretch", "stance", "flush", "hella flush", "lip", etc, etc. But not here, thank God.
The stretch of the 185/45's on my wheels will give the perfect stance with a slight poke for that toy car look. The lip will be mostly flush with the fenders, but not hella flush. ;)
 
Wider wheels-tires alone DO NOT increase mechanical grip or adhesion. Wider wheels often change the designed in scrub radius of the front suspension unless very specific compensations are applied. Incorrect wheels will also affect dynamic roll center, suspension geometry and more.
Added wheel weight increased unsprung weight which is not good for suspension-chassis performance.

Know stock wheel-tire diameter should be about 22", increasing this to 23" might appear to be trivial, yet the combined effects of the larger wheel-tire diameter, added weight, altered offset can easily add up the wrong direction seriously degrading performance rather than improving it.

7" wide wheels are about the largest for front, maybe 8" in the rear and these wheels must be of the correct offset (requires conversion to 2.5" OD springs on the struts) light weight with enough strength for real world road duty if the exxe is to be used as a road car.

205/50/15" are too big a tire, go to a smaller size.

More often than not, the alterations of wheel-tire is much about visuals or L@@Ks, much less about performance improvements. Yes, No, Maybe in this case?



Bernice
 
Bernice, I appreciate your input as well as your suggestions. Keeping these in my pocket for my next project with will be geared more for track purposes. This car will be nothing but a street car, used for getting to and from work on nice days. no twisties even on the way to work (bummer)

Odie
 
I used a 225/45 as your base line. These will show the difference from that setup.
IMO; On an 8in wheel, you should be in the 195/45 or 195/50 range. You could run a 215/45 or (50), for that squared/block look, but there again it's an opinion, and based on an 8in wheel at all four corners. 8s up front and 10 or 10.5s out back with the correct specs would be the killer setup!!
 

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Last edited:
Brayden, I am considering that air dam but don't care for the shape of the sides toward the bottom...too modern for the X in my opinion. So I was considering how it would look if they were trimmed. Your photo shows exactly what I was thinking:
IMG_20180121_153918710.jpg


The red line is where the sides originally come. But I think trimming them up (as you did) works better, which is exactly what I was thinking of doing. I also see you modified it to flow into the fender flares?
Sorry to have gone off topic. But I'd like to discuss it more, please send me a message Brayden.
 
Because I have the same airdam, and as I have talked to you about coming and getting flares, it may not be on topic directly, but indirectly it is!!
what I am doing with the tires. I have ordered 2 225's. I will use those mounted to guage if I am going to put them in front with 245 in rear, or keep them in the rear with 205's in the front.

Odie
 
Odie, Brayden sent me some info on how he integrated the air dam and the front flares. I'll let him post more here if he wishes, but basically it was a matter of trimming the two parts so they mate up. Worked out well.

Since you already have this air dam, I'd like to hear any insights you can offer about mounting it. Was it a pain requiring a lot of body work/modifications or did it easily fit without hassles?

For what its worth, in my opinion, style-wise it looks more "period correct" with the lower ends trimmed up the way Brayden did (see the highlights in the photo I re-posted above). That is how I envisioned modifying it if I decided to get one, so it helped me to see one already trimmed (thanks Brayden). Those "wedged" lower corners (as it is originally made) are a bit too modern...sort of a "canard" look that did not appear on the style scene until roughly the 2000's. With them trimmed off the lower portion flows across the entire nose, looking more like one of these spoilers (below) but with the full air-dam instead of just the spoiler:
1166_2_.jpg

cwlgs2xRR9uCeJ-UOwiBMA (1).jpg


I did a long thread about the style of the X's nose and custom designs to change the look:
https://xwebforums.com/forum/index.php?threads/front-air-dam-spoilers.33143/
 
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