Choosing Tire Sizes

Discussion in 'General Tech' started by Justang, Nov 19, 2014.

  1. Justang

    Justang Active Member

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    FOREWARD: Please do not jump to conclusions with this, I'm simply looking for feedback on fitment.


    Short story, and I will elaborate after I get some feedback:

    Front wheels are 18x8.5"
    Front tires are 275/35/18

    Rear wheels are 18x10"
    Rear tires are 285/35/18

    Please share your thoughts on this combination. Thanks all!
     
  2. wmfateam

    wmfateam Active Member

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    To much bulge on the front tires.
     
  3. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Agreed. Tire size/fit can also depend on the brand tire. For me, personally, I like to use a wheel size that's in the middle-ish of the rim width range for a given tire. For example, on a 275, the rim width might be 9" - 11"; which means anything from a 9 to an 11 will work. However, I tend to prefer a stiffer sidewall, so I'd go with a rim that was 9.5" to 10" or so. It ultimately depends on how much bulge you want and the intended purpose of the tire.
     
  4. OnyxCobra

    OnyxCobra Post Whore

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    yeah I'd go a little skinner on the front as well.
     
  5. Orange 94

    Orange 94 Moderator Staff SN95 Supporter

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    front no. back yes.
     
  6. Justang

    Justang Active Member

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    Thanks for the responses. Here's how I've arrived at this point...

    Been shopping for wheels (finally) and made my mind up over what to buy. Of course many sets are offered as a full kit, including tires, and you can save a few bucks with them.

    Case in point is nyah: http://www.latemodelrestoration.com...-Wheel-Tire-Kit-18x85-10-Chrome-Mustang-94-04

    • (2) 18x10 Chrome SC Wheels
    • (2) 18x8.5 Chrome SC Wheels
    • (2) Nitto 275/35/18 NT555 Tires
    • (2) Nitto 285/35/18 NT555 Tires

    I emailed them asking for an opinion and received the following reply:

    Basically denies my point with the first two statements, then proves my point with the last. At least that's how I see it, so I was left even more confused. I've contacted a few other places to get some other opinions, and of course wanted to see what you all thought as well. I may end up buying the wheels and tires separately.

    After doing some homework, I'm digging the Bridgestone Potenza RE760 Sports in 255/40/18 and 295/35/18. Open to thoughts on this as well. Those numbers came from me trying to scale up when compared my current 245/45/17 on 17x8 setup with respect to width, sidewall, and total diameter.
     
  7. Orange 94

    Orange 94 Moderator Staff SN95 Supporter

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    Just in my opinion that's too much tire on the front. I run 255.
     
  8. Justang

    Justang Active Member

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    Twas my primary concern. I feel a 255 would work nicely.
     
  9. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Yah, I'd take that with a grain of salt. Sure, you can run 275 on a 8" wheel. But what's the point? The section width (and thus the tread width - what actually contacts the ground) increases for a given tire with each bump up in wheel width, up to the tire's max. In other words, if you run the same tire on an 8" wheel and then a 9" wheel, the tire contact patch will be larger (which is ultimately the point/goal) on the 9" wheel than the 8" wheel. It will not be the same width, even though it's the same tire. For the Bridgestone you listed, in a 255 width, the wheel range is 8.5" to 10". Which means the guy running 275's on his 8" wheel not only was running out of the tire spec, but also means his contact patch was even smaller. He probably would have been better off running a 245, which would have fit the wheel better, *and* quite possibly ended up with a larger contact patch.

    I suggest not throwing big tires at small wheels. You'll end up with poor performance (possibly even worse than a one size smaller tire, depending on how over-sized you are), AND you'll pay more for the larger tire. If one wants to throw big tires on for bragging rights or looks, by all means, go for it. But back it up with the right sized wheels. Too big tires on small wheels, to me, is a bit like non-functional scoops. What's the point? Now, if you are just cruising the streets on Sunday drives, then sure, the 275 on an 8" wheel will last 4 years. But again, why? You aren't getting the contact patch of a 275, and you are paying more for a 275.
     
  10. Ferocious

    Ferocious Post Whore SN95 Supporter

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    That works.

    That works too.


    Tires aren't complicated. If you want them to bulge, then by all means go for a wider tire. If you want stretch, do the opposite.
    In the end all the sizes you listed will fit. It's all preference.

    I would tell you to run a 215 on the front and people would call me stupid, but at the end of the day it works.
     
  11. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Here you go: an example. Using the Bridgestone's, the RE760 Sport (used Tirerack.com as source for data):

    245 width; 7.5" - 9" rim widths --> measured on a 8" wheel, you get a section width of: 9.8"

    275 width; 9" - 10.5" rim widths --> measured on a 9.5" wheel, you get a section width of: 10.9"

    So, we can see, using a larger tire, on a larger wheel, gives a larger section width, which means a larger tread width, which means more tire on the ground.

    Now, for that guy using a 8" on the 275:

    Going down .5" in rim width knocks about 0.20" off the section width. So, on the 275, measured rim was 9.5", dude has 8", so that's -1.5", which is 3 jumps down, so -0.60" off on the section width (3 * 0.20).

    Which means the 10.9" section width on the 275 is really around 10.3" (10.9" - 0.60). So okay, 10.3" > 9.8" (from the 245 tire). But consider: you are now running your tire out of spec, it's bulging a lot so squishy sidewalls (but I guess you'd get a better ride out of it?), you are paying for 275's, and this is a back-of-the-napkin comparison of a 275 tire vs a 245 - you would think the 275 would be much, much wider. Well, it's not - when you run too small wheels. So run a tire that fits. You're car will perform better, and your wallet will thank you. If you want t3h meats, get a wheel to support it.
     
  12. OnyxCobra

    OnyxCobra Post Whore

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    Just because you CAN run 275s on an 8" wheel doesn't mean that's the right size; it's actually too wide if you consider the tire manufacturer specs. I currently have 265s on my 18x9s and 255s on my 18x8.5s.
     
  13. Justang

    Justang Active Member

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    To clarify, my intentions are neither to stretch the tires nor have a super meaty look. I'd like to try and maintain the look I currently have. Google offered up this gem: http://www.allfordmustangs.com/foru...58639-tire-wheel-picture-request-img_1058.jpg so I'll borrow that as a visual reference. I'd call it a rather ordinary fit with a tiny bulge. In my mind, to get a similar fit in front and rear, you need to have similar differences in wheels and tires. 1.5" difference in wheel width, so a 1.5" difference in tire width. 295mm - 255mm = 40mm = 1.57" so close enough. Budget is not so concerning; those Potenzas seem to get some positive feedback for the price they're at and all I have is a cruiser with more bark than bite right now.

    This is part seeking advice and part thinking out loud, so I really do appreciate any and all input given.
     
  14. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Tires don't quite work like that. If you are wanting a tire to "look" the same regarding fitment and bulge from front to rear, and you already like the wheels you have, then find a tire size that has your front wheel in the middle of the rim range, and find the other size tire that your rear wheel in the middle of the rim range, and call it a day. The amount of bulge will essentially be the same, and any difference will hardly be noticeable. It seems to me you might be over-thinking this a bit. The hard thinking comes in, IMO, if you plan on racing the car in some form and limited to class specs, or are shooting for a specific stretched look - neither of which you seem to be doing. So don't sweat it man.

    The other option is too look through pics of members rides here, find a couple you like (similar to your google search), and just ask what size tires/wheels all the way around then just do that - particularly if you are just cruising.
     
  15. Justang

    Justang Active Member

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    I'm quite certain I'm overthinking it all too. It just put me at ease hearing what others who know more have to say. Thank you for throwing in your knowledge.
     
  16. 5-oh-MUSTANG

    5-oh-MUSTANG Well-Known Member

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    i run 255/40/18 and 295/35/18 and its the same sidewall so it looks the same size
     
  17. Justang

    Justang Active Member

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    That's basically what I'm hoping for. What size wheels and would you mind posting a few pictures?
     
  18. slow90coupe

    slow90coupe Well-Known Member

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    Front needs to be a 245/40 or 255/40 and rear needs to be 295/35 or 305/35.
     
  19. FivepointSlow

    FivepointSlow Well-Known Member

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    I agree with ferocious.. theyll all work it just hinges on your preference.. im running 245s on 9 inch wheels all the way around for a little bit of a stretched look... i could fit 225s if i wanted to and could also squeeze a 295 on there..

    For the look you want id go on the smaller side (245/front 295/rear) of what [MENTION=16454]slow90coupe[/MENTION] said
     
  20. the5.ohh

    the5.ohh Legend

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    255/40/18 front, 295/35/18 rear. Perfect setup, looks identical.
    [​IMG]