Why are HP tires shorter than non HP?

[james cole]

Looking to upgrade my wheels and tires on non-HP.

Noticed that HPs are:
305/30-19 Front 26.20" Total Diameter
315/30-19 Rear 26.40" Total Diameter

VS

non-HP
255/40-19 Front 27.03" Total Diameter
275/40-19 Rear 27.66" Total Diameter
So Im a bit confused, OEM HP are much more "rubber band" not filling wheelwells as non-HP.

Im looking to add the HP wheels that specs are:
19 x 10.5”
Offset: +24mm
19 x 11”
Offset +52mm

And what I want to use on my non-HP Mustang:
OEM HP Wheels
275/35-19 Front 26.58 Total Diameter
305/35-19 Rear 27.41 Total Diameter


So will this last config work? the tires are taller than HP but a bit shorter than non-HP, so something in between.

wonder if it will rub and look reasonable with no drop, also I like a bit of sidewall stretch for handling and looks.

Thanks!
JC

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[traxiii]

You might find that the SVE MHP1 Mach1 HP copies will work better for those sizes. They are 11x19 and 10x19, your 275's will fit better on the 10" fronts and the don't poke like the HP 10.5" fronts. https://lmr.com/products/mustang-sve-mhp1-wheels-15-22

 

[james cole]

Thanks! On the HPs only the fronts poke? I plan to add the OEM fender extensions…

 

[MLO 351]

Pic of a HP car with 30 series tyres at the top and a standard Mach 1 non HP with HP rims and 35 series tyres below.

The lower pic has Continental 285/35/19 at the front and 295/35/19 at the rear, note also with HP springs front and rear installed.

If your not changing your springs to the HP versions then you will have a slightly higher gap from tyre to guard.
I would have selected 305/35/19 on the rear but no tyres available in that size at the time.

 

[james cole]

Thanks MLO! That looks great... do you happen to have any side pics to see if there is any poke?

Also no rubbing?

 

[superspartan]

You might find that the SVE MHP1 Mach1 HP copies will work better for those sizes. They are 11x19 and 10x19, your 275's will fit better on the 10" fronts and the don't poke like the HP 10.5" fronts. https://lmr.com/products/mustang-sve-mhp1-wheels-15-22

I see that installing the HP wheels on the non HP Mach 1 has a lot of quirks like the gaps mentioned and speedometer variance. Do the SVE wheels also have that issue on the non HP Mach 1?

 

[MLO 351]

Thanks MLO! That looks great... do you happen to have any side pics to see if there is any poke?

Also no rubbing?

Have messaged you.

 

[traxiii]

I see that installing the HP wheels on the non HP Mach 1 has a lot of quirks like the gaps mentioned and speedometer variance. Do the SVE wheels also have that issue on the non HP Mach 1?

The speedo issue would be with the difference in diameter, not with the wheels. The OEM fronts poke a bit, the SVE's don't, and also give 1/4" more room on the inside too.

 

[Bobby57]

I see that installing the HP wheels on the non HP Mach 1 has a lot of quirks like the gaps mentioned and speedometer variance. Do the SVE wheels also have that issue on the non HP Mach 1?

The speedometer issue is easily remedied with a straight-forward ForScan adjustment

 

[Charlemagne]

Chinese replicas for higher price than USA made originals? Not for me, haha.

The poke is very small, edge protector mostly (with my 285/35 at least):

 

[RobZ71LM7]

Not what you asked but here’s HP springs and 305/30/19 on all 4 wheels. The Non-HP size (same as PP1 tire size) in my opinion has the taller sidewall for more comfort. In 305’s there are many more tire options with a 30 series versus 35 series aspect ratio.

 

[james cole]

Chinese replicas for higher price than USA made originals? Not for me, haha.

The poke is very small, edge protector mostly (with my 285/35 at least):

This actually looks good... did you do any camber adjustment?

What tire size are you running rear?

 

[NightmareMoon]

The reason they're shorter is because those are the sizes that the tire manufacturers are making in the specific sticky tires the HP is running. 305/35R19s aren't available.

Mach1 HP is a lower volume model, so Ford isn't going to spec out and work with the tire manufacturers to produce an entirely unique tire which isn't in the tire manufacturer's current lineup.

Also there are minor benefits from the small amount of free center of gravity lowering from the smaller tires.

If you're not running sticky tires with ultimate 10/10ths handling as the top and only priority, then you're free to run whatever size you want. For most drivers and street cars you definitely don't need the absolute stickiest tire.

 

[Charlemagne]

This actually looks good... did you do any camber adjustment?

Nope, it's still stock from factory. Gonna ask to check that when I go for first oil change.

What tire size are you running rear?

305/35 in the rear (Michelin Pilot Super Sport).

Imo these wheels are great for nice flush look and wide tyres in profile 35 for nice wheel gap.

 

[james cole]

Beautiful, no rubbing at all even at full lock?

Did you notice a decrease in power since the wheels weight more?

You just gave me all the info I needed... thanks!
JC

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