Tire/wheel fitment

[Royalstorm]

Question about fitment and hoping for a quick answer. I’ve got a 2021 GT2 with summer wheels/tires and want to make sure front will fit without rubbing. 245/35R-19 on 19x8.5 wheels. Anyone running similar setup and can confirm this will work? Of note: rear will be 255/35R-19 on same wheels.

 

[Snicklefritz]

offset in front should be 35 or less and you should have no problems clearing in front. you can't run the oem rear wheels in front without spacers. I run 225/40R-19 tires in front on 8.5 +40, and I don't know if a 245 would rub or not with that much offset.

 

[Ohiocruiser]

Is yours awd or rwd? Running different diameter tires is a big no on awd.

 

[Royalstorm]

offset in front should be 35 or less and you should have no problems clearing in front. you can't run the oem rear wheels in front without spacers. I run 225/40R-19 tires in front on 8.5 +40, and I don't know if a 245 would rub or not with that much offset.

Thanks. Yeah offset is 35mm so hopefully all will work. Appreciate the help!

 

[Snicklefritz]

oem od difference in staggered is 2mm smaller in the rear. would running a 245/35 in front be a problem? it's only 7mm more smaller.

Is yours awd or rwd? Running different diameter tires is a big no on awd.

 

[Royalstorm]

Is yours awd or rwd? Running different diameter tires is a big no on awd.

It’s AWD but my understanding is stock runs staggered anyway—225 in front and 255 in rear so if anything this is closer to a square setup than stock, no?

 

[Snicklefritz]

It’s AWD but my understanding is stock runs staggered anyway—225 in front and 255 in rear so if anything this is closer to a square setup than stock, no?

you are talking width and offset, @Ohiocruiser is talking od differences, see my post above yours questioning if an additional 7mm of smaller od in the rear (making 9mm difference over all, less than 2% smaller in the rear) would affect an awd system negatively. I don't know but suspect there would no issues.

 

[Royalstorm]

you are talking width and offset, @Ohiocruiser is talking od differences, see my post above yours questioning if an additional 7mm of smaller od in the rear (making 9mm difference over all, less than 2% smaller in the rear) would affect an awd system negatively. I don't know but suspect there would no issues.

Ah, ok that makes sense. Thanks for clarifying. I’m still trying to make sense of the whole wheel/tire size, offset, diameter business and forgot that buying a 19 tire doesn’t translate into guaranteed identical diameter if tire width is different.

 

[Snicklefritz]

thinking about this some more, I now wonder if this starting difference of 9mm is wise. on the staggered setup the starting difference is 2mm smaller in the rear (negligible), but rear tires wear about twice as fast as front tires do, some drivers getting even less life out of the rears than that. the point is, by the time the rears are shot on oem sizes, there will likely be 5-7mm difference in od front to rear, this seems built into the design and tolerances of the awd system. to double that difference with the tire sizes that you are suggesting would take the percentage od difference well over 2%, and iirc from reading from those who 'know' this is dangerous territory for an awd, it puts stress on the system.

 

[Volfy]

Yeah, the built-in tolerance is meant to take care of variances in normal operation, such as differences in wear, tire pressure, camber angle, and ballooning at high speeds. The more you eat into that to play around with tire sizing, the less margin you will have left for what it was designed for.

If this were my AWD Stinger, I would make sure front and rear tires have the same effective rolling diameter (within 1%). Just as an example, the stock Michelin front 225/40R19 and rear 255/35R19 differ in rolling diameter by only 0.25%. It's listed differently on the various sources. Tire Rack lists them as "Revs per Mile", which is a measured parameter more representative of effective rolling diameter than either calculated or listed diameter.

 

[Royalstorm]

thinking about this some more, I now wonder if this starting difference of 9mm is wise. on the staggered setup the starting difference is 2mm smaller in the rear (negligible), but rear tires wear about twice as fast as front tires do, some drivers getting even less life out of the rears than that. the point is, by the time the rears are shot on oem sizes, there will likely be 5-7mm difference in od front to rear, this seems built into the design and tolerances of the awd system. to double that difference with the tire sizes that you are suggesting would take the percentage od difference well over 2%, and iirc from reading from those who 'know' this is dangerous territory for an awd, it puts stress on the system.

Great information! I appreciate you taking the time to walk through that. I have decided to return the 245s and the use the 225s that are recommended in the front.

 

[Royalstorm]

Yeah, the built-in tolerance is meant to take care of variances in normal operation, such as differences in wear, tire pressure, camber angle, and ballooning at high speeds. The more you eat into that to play around with tire sizing, the less margin you will have left for what it was designed for.

If this were my AWD Stinger, I would make sure front and rear tires have the same effective rolling diameter (within 1%). Just as an example, the stock Michelin front 225/40R19 and rear 255/35R19 differ in rolling diameter by only 0.25%. It's listed differently on the various sources. Tire Rack lists them as "Revs per Mile", which is a measured parameter more representative of effective rolling diameter than either calculated or listed diameter.

As I said in another comment, I appreciate your explanation. That is very helpful. I certainly do not want to add stress to a system that is unnecessary. I will be returning the 245s and switching to 225s in the front. Thanks again for your help.

 

[Snicklefritz]

so far, I've stayed with the oem staggered sizes for tires, even though I have aftermarket wheels that are 8.5 wide in front and 9.5 wide in the rear. this added stretch stiffens the side wall. although some don't like the look a little stretch is okay. if you are running 8.5 wheels front and rear it gives you options of going to the same sized tires front and rear. some have run 255s square, and depending on your offset you could do it with or without spacers in front, rear won't be an issue. on an 8.5 wide wheel the most common squared size wider than oem is 245, judging by what I read on here.

 

[Redleg94]

so far, I've stayed with the oem staggered sizes for tires, even though I have aftermarket wheels that are 8.5 wide in front and 9.5 wide in the rear. this added stretch stiffens the side wall. although some don't like the look a little stretch is okay. if you are running 8.5 wheels front and rear it gives you options of going to the same sized tires front and rear. some have run 255s square, and depending on your offset you could do it with or without spacers in front, rear won't be an issue. on an 8.5 wide wheel the most common squared size wider than oem is 245, judging by what I read on here.

I have the same setup for my summer tires.