Tire Questions.. Taller Tire In The Front.

Discussion in 'Fox 5.0 Mustang Tech' started by billison, Jun 20, 2013.

  1. Ok. So the only thing left to do is replace my tires and I'll be driving my 92 on Saturday.

    So I'm researching what size to go with, and I want to keep my quad shocks. And I keep seeing tires that are set up

    255/40 rear and 245/45 in the front.. The. 45 is a taller tire right? Is there a reason for this?

    Cuz I'd rather have my rears be taller/wider than my fronts. My front is too high as it is. The rims are 4 lug 17x9 cobra r's.

    As of now I'm thinking 245/40 in the front and 255/40..

    Not sure if. 235/40 would work on the front and 255/45 in the rear.

    I've never ordered tires.. Sorry for the noob questions.
  2. To keep it the same height use a 225/45 up front if your using a 255/40 in the rear. Thats what I'm running on my SSC.
  3. If anything, I want the front lower..
  4. Just know if you use different size tires that is going to impact your ability to properly rotate the tires front to back, which is preferred over side to side, resulting in a decreased tire life.
  5. ^^^ a non issue.
  6. null_zpsd5930b08.jpg


    I think they are 245/45 in the front and 275/40 in the rear. I'm fling 255 in the rear so I can install my quads. But the front is way too high. I know the tires will only do so much but I don't wanna do springs till winter.
  7. A 245/45/17 will technically fit the front, but on 17x9" wheels, they're going to be stretched to the point of foolishness. I've got 255/24/17's on my 17x9's and even they're too stretched for my taste. I really wished there were a bigger selection of 8" wheels made. You could go with 275's all the way around, but expect to do some hammering and modifying up front to keep them from rubbing.....and you'll certainly lose the quad shocks in the rear.

    If it were me, I'd just cut about 1/3 of a coil off of my front springs and call it a day.
  8. Buying tires before springs huh? Not sure i'd do that without a lot of research and knowing exactly what ride height you're going to get and what tires will squeeze in there.

    Also, there is a tire calculator (just google search it) and it will tell you the width and height (overall diameter is what you want to know right now) so you know what size a 255/45/17 tire will be. Also certain brands only make certain sizes.

    I have staggered tires too, wide in back and narrower in the front but i'll drive my car about only 1k miles per year.
  9. Mine is gonna be a weekend driver. And I'm tossing cheap used tires on to get me through the summer for just this reason, I'll be swapping out springs/shocks/ and rear brakes come winter, once the ride height is set, it'll get new tires, for now i want to clear my quads and get the front down a tad.
  10. Why are you so bent on keeping your quads? Believe it or not, I removed mine and drove it for over a year before I got my new upper and lower control arms. Never got a hint of wheel hop that whole time. Couldn't hurt to remove them and give it a try. It'll free up all kinds of room back there.
  11. My quads are currently removed and I have super bad wheel hop even with aftermarket control arms. But my main question has not been answered, is there any reason I would want/need the taller tire in the front? Otherwise I'll be going 40's in the front and 45's in the rear. I'm looking at the stance of the car and less of how the tire looks on the rim ( for now).
  12. You won't want a 40-series tire on the front, unless you plan on going with 275's. Anything else will be far too short. You still want to keep the stock over all diameter. A 245/45/17 is the stock tire height for a 17" rim. Unfortunately, because you have 9" wheels and 245mm tire is going to be really stretched on there. A 255mm is a little better, but it's still just barely square and it does an about 1/4" more to the ride height. You don't "need" a taller tire, but that's just about your only option in a 45-series tire if you want to increase the width. A 275mm tire is the best match for a 9" rim and in a 40-series tire it would allow you to keep the stock diameter, but it's unfortunately too wide for the fox's front track. It's going to get you some major front end contact unless you make some heavy modifications...especially if you lower the car.

    Quite frankly, a 9" wheel is too wide for the front end of a Fox, but since they work well with SN95's and S197's, that's the rim size most aftermarket rim manufacturers make.
  13. I see!! Is there a reason to keep the rear 40's or can I bump it up to 45? Or is the stance just not gonna chance till I swap springs? And maybe hunt down 17x8 rims for the front
  14. I suggested 40's in the rear if you were going to go with a 275mm tire. That would keep your stock diameter. You could go with a 255/45 in the rear on your 9" wheels as well....that would ensure good rotation.
  15. I've been messing with the tire calculator, that really helps.
  16. Ok, so my question is this. Do I need to have the same diameter tires front and rear? At this point I wanna know how to pick proper sizes and do it myself .
  17. You don't need to, but why wouldn't' you want them to? Your tire sizes are limited, but the tires available....and for a 17x9" wheel, you've only got a few to choose from.

    If it were me, I'd go with 255/45/17's all the way around.
  18. You want the diameters close for aesthetic reasons if nothing else. It sounds like you're struggling with tire height vs aspect ratio.

    245 = tires' section width (sidewall to sidewall) in millimeters
    45 = aspect ratio, or the percentage of section width represented by the sidewall height. In plain English, this tire's sidewall is 45% as tall as the tire is wide.
    17 = wheel diameter, in inches.

    So a 245/45-17 is 245 mm wide, each sidewall is (245 x 0.45 = 110.25mm) tall, and the tire's overall diameter is (110.25 x 2 = 220.5mm or 8.7 inches) + 17 inches = 25.7 inches tall.

    If you go wider on the tire, you have to go shorter on the aspect ratio to keep the same diameter. For example, if you do the math, you'll see that a 275/40-17 is almost exactly the same height as a 245/45-17.

    All that said, the tread widths are nominal, meaning they vary considerably within the same number. For instance, it's well known that Nitto's tend to run on the narrow side for any given size marking. Recently my eyes bugged out of my head when I was at the tire shop and I saw one of my 255/40-17 Hankook RS-3's next to a Michelin (I think) 255/40-17 tire that had come off a Porsche. They had identical tire size markings, but the other tire was at least 1.5 inches wider than mine. That's the most ridiculously extreme example I've ever seen, but it just goes to show, it pays to stick with one manufacturer on all 4 tires if for no other reason than sizing.
  19. I'm starting to get a feel for it all now. I'll look over the math and make a decision and post pics tomorrow. Again, I'm just tossing on cheap-o used tired to get me through the summer , I gotta start driving this think or it's gonna kill me. That said, I'm already collecting parts for my winter project, I'll be dropping it down and going 4 wheel disk ( already got the Tc rear brakes) and newer( smother) shocks, so once all of that is done, I'll be dropping some real cash on good tires.
  20. tc rear axles are 3/4 inch longer each side so dont expect it to bolt up right without the axles.