I don't understand wheel width (9J/9.5J/10J)

Nodster

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Hey

I'm sorry for being so dumb and asking this but I'm still on the hunt from some different 19" wheels for my car. My plan - I want to fit winter tyres to the current stock wheels. I then would like a new set of alloy wheels that would take a wider tyre up front and rear (not by much but just something to help with the extra BHP from the Vortech kit I'm fitting in Spring). By the time I figure this out without asking for help it'll be too late. So here goes... 🤭

I've been looking at aftermarket wheels thinking, this will be dead easy, I need 19x9 upfront and 19x9.5 on the rear. Then I can go purchase my winter tyres which I've bookmarked. I know the ET (45 / 52.5 respectively), Bore (70.5 mm) and PCD (5x114.3). Smashing lets go. Thing is, every search I do I can't find those wheel sizes. It's either something like 19x8.5 front and 19x9.5 rear. What, wait, where is the 19.9 please? Or then rear, 19x10. Which just gets me so confused thinking, well is 19x10 OK? Will it fit? If it is wider, do I need a different offset? What tyre do I even put on 19x10 (can it take a normal 275 tyre)?

Please help! Before I go mad. 😂

It seems like everyone here understands this and I see so many people with aftermarket wheels but I can't get my head around it.

Thanks.

 

cerbomark

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19x10 will fit 285 s and up. I would use them for summers and your stock for winter I think. Buy from a retailer that specs them for mustang like LMR. They did the rest as far as offsets and center bore stuff.
 
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And so 285/35/19 front and rear will not upset the speedo or tolerances moving from a 255/40 and 275/40?

But I agree yes, I would use the stock for the winter tyres and the new wheels for the summer. Totally agree with that approach.
 

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NightmareMoon

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19x10 ET35 with 285/35R19 tires all around works really well.

Speedo might be off marginally, but its close enough.
 

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I had the same issue. I used stock tires size and had 19x10 for the rear. The tire fit so well that I completely forgot the winter rims were half an inch larger. It's tire/rim height that'll upset the speedo, not the width.


That all being said, ideally, you would actually want to run a thinner tire for winter. 255 squared set up would let you rotate and also cut through the snow better. I stayed with staggered because I couldn't figure out how to get a package deal, at tirerack, using an off size. So it depends if you want to use it more for dry/cold weather use or actually in the snow.
 

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And so 285/35/19 front and rear will not upset the speedo or tolerances moving from a 255/40 and 275/40?

But I agree yes, I would use the stock for the winter tyres and the new wheels for the summer. Totally agree with that approach.
You're mixing several different issues.

Items A. Will a tire fit practically and safely on a wheel.
Item B. Just because it fits on the wheel, will the wheel/tire clear all the other components of the car through natural use (suspension travel and/or turning) without making contact (rubbing fender liners, touching suspension parts, binding against fenders, etc)
Item C. Does a change in tire diameter alter the vehicle speed/odometer functions.

Item B depends on what the configuration of the suspension is. Is it stock/OEM or is it lowered? Do you have plans on lowering it in the future?

Item C is easily resolved through either a tune adjustment OR through FORSCAN. As I understand it, you can do one but not both (if the tune is triggered to use it's parameters it will ignore the forscan parameters.)

Ford now uses input from the wheel sensors (rather than a transmission based speed sensor at the transmission or a transmission based speedo gear). So yes, if you increase or decrease the radius of the wheel/tire it will have an effect on the vehicles speed and mileage output. Ironically, adjusting it artificially is a backdoor to odometer fraud (in theory you could change the inputs to say that the wheel/tire is very tiny and drive around with your speedometer at half of actual speed. Over the course of 20k miles, the odometer would read 10k miles traveled).

The easiest thing at this point is to describe your car setup and ask others whether a particular wheel/tire setup will work and what the impacts will be (and how to adjust the speed calcs).
 

MAGS1

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This will help you with your overall tire height and speedometer. I believe the general rule of thumb is to stay within 3% (+ or -) of your original tire height. An difference greater than that throws off the speedo by a good amount and also affects mpg calc and a few other things. Unless you have access to forscan to change tire size in the computer.

https://tiresize.com/comparison/
 
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Nodster

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I had the same issue. I used stock tires size and had 19x10 for the rear. The tire fit so well that I completely forgot the winter rims were half an inch larger. It's tire/rim height that'll upset the speedo, not the width.


That all being said, ideally, you would actually want to run a thinner tire for winter. 255 squared set up would let you rotate and also cut through the snow better. I stayed with staggered because I couldn't figure out how to get a package deal, at tirerack, using an off size. So it depends if you want to use it more for dry/cold weather use or actually in the snow.
Thanks - oh yeah it'll mostly be cold, damp, freezing weather. We rarely get proper snow here and if we did it would be a dusting. That's all we need to grind the UK to a halt. 🤭 So it's more temperature and safety as the current tyres don't handle well under around 9ºC or lower. Today was -1ºC and frosty and I didn't dare use the GT. Popped out in my Dad's Q3 instead.

You're mixing several different issues.

Items A. Will a tire fit practically and safely on a wheel.
Item B. Just because it fits on the wheel, will the wheel/tire clear all the other components of the car through natural use (suspension travel and/or turning) without making contact (rubbing fender liners, touching suspension parts, binding against fenders, etc)
Item C. Does a change in tire diameter alter the vehicle speed/odometer functions.

Item B depends on what the configuration of the suspension is. Is it stock/OEM or is it lowered? Do you have plans on lowering it in the future?

Item C is easily resolved through either a tune adjustment OR through FORSCAN. As I understand it, you can do one but not both (if the tune is triggered to use it's parameters it will ignore the forscan parameters.)

Ford now uses input from the wheel sensors (rather than a transmission based speed sensor at the transmission or a transmission based speedo gear). So yes, if you increase or decrease the radius of the wheel/tire it will have an effect on the vehicles speed and mileage output. Ironically, adjusting it artificially is a backdoor to odometer fraud (in theory you could change the inputs to say that the wheel/tire is very tiny and drive around with your speedometer at half of actual speed. Over the course of 20k miles, the odometer would read 10k miles traveled).

The easiest thing at this point is to describe your car setup and ask others whether a particular wheel/tire setup will work and what the impacts will be (and how to adjust the speed calcs).
I know, sorry, this is what runs around in my head. lol

ITEM B: No plans to lower. The roads here are too bad and far too many speedbumps or sunken manhole / inspection chambers in the roads to make lowering anything other than a misery.

So to summarise.

Currently have 255/40/19 up front and 275/40/19 rear. On 19x9 and 19x9.5 stock Ford wheels. I'd like to use these with the winter tyres I have saved. The winter tyres are same size so should be a nice easy straight swap. No issues.

New wheels. I'd like to go slightly larger (tyre size). From the previous posts it seems the SVE wheels from LMR.com would fit the bill. 19x10 all round with a 285/35/19 tyre (so giving me the slightly wider tyre). And these then become my new summer setup.

Thanks
 

MAGS1

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Thanks - oh yeah it'll mostly be cold, damp, freezing weather. We rarely get proper snow here and if we did it would be a dusting. That's all we need to grind the UK to a halt. 🤭 So it's more temperature and safety as the current tyres don't handle well under around 9ºC or lower. Today was -1ºC and frosty and I didn't dare use the GT. Popped out in my Dad's Q3 instead.



I know, sorry, this is what runs around in my head. lol

ITEM B: No plans to lower. The roads here are too bad and far too many speedbumps or sunken manhole / inspection chambers in the roads to make lowering anything other than a misery.

So to summarise.

Currently have 255/40/19 up front and 275/40/19 rear. On 19x9 and 19x9.5 stock Ford wheels. I'd like to use these with the winter tyres I have saved. The winter tyres are same size so should be a nice easy straight swap. No issues.

New wheels. I'd like to go slightly larger (tyre size). From the previous posts it seems the SVE wheels from LMR.com would fit the bill. 19x10 all round with a 285/35/19 tyre (so giving me the slightly wider tyre). And these then become my new summer setup.

Thanks
The 285/35r19 is a great setup and a very popular one. Can’t go wrong there. You can even go 275/40r19 all the way around on 19x10 if you want to fill the wheel gap a little bit.
 
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Nodster

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Thank you everyone so far - this has been really helpful.
 

NightmareMoon

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So to summarise.

Currently have 255/40/19 up front and 275/40/19 rear. On 19x9 and 19x9.5 stock Ford wheels. I'd like to use these with the winter tyres I have saved. The winter tyres are same size so should be a nice easy straight swap. No issues.

New wheels. I'd like to go slightly larger (tyre size). From the previous posts it seems the SVE wheels from LMR.com would fit the bill. 19x10 all round with a 285/35/19 tyre (so giving me the slightly wider tyre). And these then become my new summer setup.

Thanks
Solid plan!
 

 
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