305s rear tires

[5.0hopeful]

Noticeable?

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[DRKHORS]

Noticeable?

I went from 265/35's to 315/35's and my speedometer is off apprx 3mph. Now, if you want to get real technical, when figuring in parallax (angle from driver's position to the speedometer needle) it's almost dead on.

Here's you a good tool to check out to compare changes to the wheels, tires, and speedo that come into play with upsizing...
http://rimsntires.com/specspro.jsp

 

[Paul@PKAUTODESIGN]

Does the new 305 rear size throw off the speed reading?

the 305 will change the speedo a bit but not by much.

 

[Donthatemyhonesty]

the 305 will change the speedo a bit but not by much.

Have a ?i just ordered the velgan vmb7s for 2018mustang gt 275 35 20 front and 305 35 20 rear will i have to adjust anything or will it be fine thanks oh and i have it lowered on eibach pro kit

 

[BmacIL]

Have a ?i just ordered the velgan vmb7s for 2018mustang gt 275 35 20 front and 305 35 20 rear will i have to adjust anything or will it be fine thanks oh and i have it lowered on eibach pro kit

If you have the non-PP1 wheels, the new rears are 0.9-1.2" larger diameter (depending on which stock wheel), so your speedometer will be off a good amount. 305/30R20 would be almost the same diameter as stock.

 

[Donthatemyhonesty]

If you have the non-PP1 wheels, the new rears are 0.9-1.2" larger diameter (depending on which stock wheel), so your speedometer will be off a good amount. 305/30R20 would be almost the same diameter as stock.

Thanks will i have any issuses with rubbing at all thanks for your advice

 

[BmacIL]

Thanks will i have any issuses with rubbing at all thanks for your advice

If you're not lowered, unlikely. If you are, depends on your alignment and wheel offset.

 

[Donthatemyhonesty]

If you're not lowered, unlikely. If you are, depends on your alignment and wheel offset.

Thanks for your advice

 

[Mazman]

I am running 305/30/20, lowered but not by much.

Have never had any issues with rubbing.

20x11" on the rears, ET50

 

[fmc_smt]

305/30/20 front 255/35/20 front dropped about 1.5 inch no rub . Offset 35 rear 45 front rim width 9.5 front 10.5 rear

 

[robwlf]

lowered on bmr min drop 275/35/20 front .. 305/35 rear .. 20x10 front 35 offset ...20x11 rear 55 offset never a prob might even go lower next spring also -1.6 rear camber -1.8 front View attachment 387072

 

[Donthatemyhonesty]

If you have the non-PP1 wheels, the new rears are 0.9-1.2" larger diameter (depending on which stock wheel), so your speedometer will be off a good amount. 305/30R20 would be almost the same diameter as sto
ck.

Here is a pic of mine injust did, i think i might go with 305 30s next time in back but picture doesnt do the car justice

 

[Andy13186]

I like taller tires, i had 315 35 20s and currently have 295 35 20's makes the car look lowered without having to lower it since it takes up the wheel gap alot better. Can adjust the tire height with your tuner easily if you are tuned. I dotn know if they fit on a lowered setup. I had 315 35 20s on my lowered 2011 mustang and I had to put the stock spring back on the rear to not rub. I had no issues at all on the stock pp1 ride height with 315 35 20s on my 18 though. looks great too.

 

[Donthatemyhonesty]

I like taller tires, i had 315 35 20s and currently have 295 35 20's makes the car look lowered without having to lower it since it takes up the wheel gap alot better. Can adjust the tire height with your tuner easily if you are tuned. I dotn know if they fit on a lowered setup. I had 315 35 20s on my lowered 2011 mustang and I had to put the stock spring back on the rear to not rub. I had no issues at all on the stock pp1 ride height with 315 35 20s on my 18 though. looks great too.

Thanks

 

[rsmustangjr16]

You can also use Forscan to change the tire size. I went from 275/40/19 in the rear on a PP1 to a 305/35/19 and my speedo was fast by 3mph. I corrected it via Forscan and now its only off by an mph:

https://docs.google.com/spreadsheets/d/1mWnuQZlDTUGjKjmJje1QJIR8Z2c7Kf8KBZxKnw_8EqU/edit#gid=0

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