Whipple 05 GT 10 psi boost tires

Discussion in 'Tires and Wheels' started by 05GrayGT, Sep 20, 2020.

  1. 05GrayGT

    05GrayGT Junior Member

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    Hi all,

    My 05 GT is in desperate need of new tires in the rear (I hope that will help) Currently running nitro nt555 255 in front and 275 in rear. They have tread left but they break loose so easy and I have little confidence while driving around turns, may also be age of tire as they are probably 6+ years old now. Without changing wheels what is a good size tire and recommended tire for grip from those with experience. I have american muscle 18x9 in the front and 18x10 in back. I don’t track the car. It’s just driven occasionally almost exclusively in good weather. Just want to keep enjoying it on the road and have a little more confidence in it. Thanks all
     
  2. Norm Peterson

    Norm Peterson corner barstool sitter

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    There are many choices that will be better than NT555's. It was already an old tire series when you bought yours, just popular due to AM and others pushing them on price.

    10" wide rear wheels is going to limit how wide you should go especially given that confidence while cornering is high up on your list of priorities. But there still is fairly good selection in 275/40-18, which should work well with 255/45-18 front tires on their 9" wide wheels. I suspect that Continental's ExtremeContactSport would be one of your better options.


    Norm
     
    46addict likes this.
  3. 05GrayGT

    05GrayGT Junior Member

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    Thank you Norm, very helpful. I was thinking going to a wider tire like a 285 would also help but maybe not necessary with a better quality tire.
     
  4. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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  5. Norm Peterson

    Norm Peterson corner barstool sitter

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    A 255/45-18 and 285/40-18 combination would be my first choice (it's what the 2008-ish GT500 came with from Ford). The only sticking point is that there aren't as many choices. Only two at Tire Rack (the Conti ExtremeContactSport again, and what looks like the original GT500's Goodyears which weren't all that great a decade ago).

    Whether your car is lowered, and if so by how much may have to be considered. As would any difference in front vs rear tire diameter assuming that your car has ABS.


    Norm
     
  6. AHaze

    AHaze Junior Member

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    I currently have 275/35-19 Firehawk Indy 500s on my Vortech blown '05 and can't recommend them enough for a street car. I have more confidence pushing the car hard now than when it was NA on GT500 spec Goodyears.
    Admittedly, there are better tires but you start getting into very small improvements for large increases in price.
    Unfortunately they only have a 275 in 18" so you also have to decide if you can live with that.
     
  7. 46addict

    46addict 13726548

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    Falken Azenis FK510 and General G-max RS are also good tires in the $170 range. Anything much cheaper than that seem to be cheap Chinese tires.
     
  8. tabstang

    tabstang Junior Member

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    I second the recommendation for Firestone Firehawk Indy 500's - you really can't beat them for the $, grip like mad, smooth ride, not noisy, good feedback. Running them on my boosted 07 GT with full race suspension - these are outstanding tires
     
  9. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    I'm wondering of those suggesting a "street" tire, how many of you run a PD blower?

    IMO, having owned a blown 06GT (460 whp) and now my Shelby... you want consistent traction, you need a DR.

    OP posted it was not a DD, driven in good weather, a PD blower hits much harder than a centri.
     
  10. Norm Peterson

    Norm Peterson corner barstool sitter

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    OP also clearly mentioned wanting more confidence in the corners. I'm not seeing drag radials being any better at that than the NT555's he currently has (and quite possibly not even as good).


    Norm
     
  11. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    Norm -

    I took the corner issue due to the ties breaking traction
     
  12. AHaze

    AHaze Junior Member

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    Honest question: Does a drag radial running at street tire temperature offer much better grip than a good street tire? I know they stick like mad once you get 'em good and hot but that doesn't do you much good on the street.
    I won't run a DR on the street for other reasons (a surprise rain storm with half worn DRs doesn't look like much fun) but I'm tempted to try the Bridgestone RE-71R once the Indy 500s are done.
     
  13. Norm Peterson

    Norm Peterson corner barstool sitter

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    That part needs a driver mod and possibly a tune with less aggressive tip-in response rather than a tire mod. I was trying to avoid going there, even though most summer tires these days represent a clear upgrade over NT555's.


    Drag radials aren't as stiff laterally as a summer performance tire (the extra compliance that softens the hit is what DRs give up in exchange for the better launch and low gear traction). Rear tire lateral stiffness is one of your best friends in corners taken with much enthusiasm. You sometimes see this same thing at the drag strip where a car gets somewhat "woozy" at the big end when the rear tires are being run at inflation pressures that are too low for solid lateral stability.


    Norm
     
  14. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    100% they do with a higher HP car - normal street driving

    https://www.instagram.com/p/CEPTDZan-XA/?utm_source=ig_web_copy_link

    Norm - full agreement that a DR is not a tire to "corner carve" with, however, if they are not aired down, they handle most curves on the street fine in my experience, most of the warning speeds on curves on long on/off ramps can be maneuvered easily at or even slightly above those posted warnings.

    again I took the OP's comment as "my tires are worn out so they spin in a curve" which to me means he's got more power than the worn tire can take and needs an upgrade
     
  15. 05GrayGT

    05GrayGT Junior Member

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    Thanks everybody. Leaning towards the Indy500s after all the feedback in the 275s. To answer a posters question the car is lowered 1.5”. Thanks
     
  16. RavenGT

    RavenGT Member

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    275? Those wheels will fit 285s with ease. Go with the widest tire that will fit. The Firestones are perfectly fine for the street.
     
  17. Norm Peterson

    Norm Peterson corner barstool sitter

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    285s will fit the wheels, sure, but after that the combination has to fit the car. Amount lowered (which we didn't know until this morning) and wheel offset (which we still don't know) both figure in to whether they'll work. and at 1.5" lowered it could come down to needing the specific dimensions of the tires chosen.


    Norm
     
  18. Norm Peterson

    Norm Peterson corner barstool sitter

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    I'm afraid that's not much of a recommendation (IIRC from long-ago highway design class they're designed to lateral g's that are quite low, on the order of a quarter of a g), and it doesn't address emergency maneuvers at all where you'd instinctively 'swerve'.

    Never mind any Cars & Coffee departures . . .


    Understood.

    But that puts it on the driver to keep the total of cornering force and forward traction force within what the tire can hold. Careful throttle modulation vs stomping on it.

    Cornering force doesn't go away just because the driver decides to get into the throttle, and if there's much cornering force going on even a DR is going to be traction-limited to a good bit less than it would be in the straight lines that it was designed to excel at. A DR's extra distortion in the corners vs a summer performance tire most likely means that any given amount of cornering will hurt forward bite with DRs more than with summer perf tires.

    All tires gradually heat-cycle down to lower performance capabilities. If there's anything here, it's that a DR will heat-cycle out a good bit faster than any true summer performance tire. More like the current crop of "autocross special" 200-TW tires and weenie R-comp road race tires. This isn't a street-friendly characteristic, and it would put OP in nearly the same situation sooner after running up some miles and hard use.


    Norm
     
    Last edited: Sep 23, 2020
  19. shard phoenix

    shard phoenix Member

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    I run the eagle f1 supercar 3 in 285/35r19 on all four for summer tires on mine, whipple blower, custom tune etc like them very much.
     
  20. Racer47

    Racer47 Doesn't have much to say S197 Team Member

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    Drag radials get a much worse name than they deserve for cornering. Go to any competitive autox and you'll see drag radials. There are a bunch of ET Street SS being used around here. They have a ton of traction and come in different sizes than typical tw200s. I had a pair of Nitto dr's years ago and had no cornering issues in fact it made the car push more due to all the rear grip.

    My daily tires are 295s on 10" rears and 275s on 9" fronts. I'm lowered a lot, don't know how much but certainly more than 1.5". Everything clears. But I get tired of constantly debating tires. Everybody is an expert but how many of them have used a lot of tires? I burn up a set a year, on average, combining both street and race tires.

    Firerock 500's only seem like a good tire, if you've never had really good tires.

    And yes, drag radials do offer a lot more grip at normal pressures and normal (non burn out) temps. I don't have any experience with the M&H listed above but I can tell you that the ET SS's stick very well, extremely well, under normal driving.
     
    Last edited: Sep 23, 2020
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