[nielsensmn]

I have a 2008 Mustang GT/CS and would like to add wider tires to the rear. I have the 18' chrome wheels on the car and have dropped it 2'. What is the largest size tire I can fit on the stock 18's? What is the largest size tire I can put on the rear without rubbing and that will fit in the wheelwell using a larger 18' rim?

[sqidd]

Originally Posted by nielsensmn

I have a 2008 Mustang GT/CS and would like to add wider tires to the rear. I have the 18' chrome wheels on the car and have dropped it 2'. What is the largest size tire I can fit on the stock 18's? What is the largest size tire I can put on the rear without rubbing and that will fit in the wheelwell using a larger 18' rim?

Different brand tires have different rim width requirements. You will need to find some tires you like and then see if they will fit the rims. You will most likely be limited to a 245mm tire unless you can find a manufacturer that built their tire to fit on a narrow rim.

How wide are the stock 18" rims?

You can't pick a tire that fits those rims that will rub. You can go with a 295mm tire on the back and there is no way you can mount those on the stock rims.

[johnnshepherd]

Originally Posted by sqidd

Different brand tires have different rim width requirements. You will need to find some tires you like and then see if they will fit the rims. You will most likely be limited to a 245mm tire unless you can find a manufacturer that built their tire to fit on a narrow rim.

How wide are the stock 18" rims?

You can't pick a tire that fits those rims that will rub. You can go with a 295mm tire on the back and there is no way you can mount those on the stock rims.

I work at Discount Tire. Biggest you can go is 255/45/18 on those wheels.

[stlwagon]

Originally Posted by johnnshepherd

I work at Discount Tire. Biggest you can go is 255/45/18 on those wheels.

+1... 255s are as big as you should go.

[nielsensmn]

Is that the largest for that certain rim? If I buy larger 18' rims for the rear, what would be the largest tire to fit in the wheelwell of that vehicle?

[stlwagon]

Originally Posted by nielsensmn

Is that the largest for that certain rim? If I buy larger 18' rims for the rear, what would be the largest tire to fit in the wheelwell of that vehicle?

If you go with a 10" rim out back you could fit 295s or larger.

[stkjock]

Originally Posted by johnnshepherd

I work at Discount Tire. Biggest you can go is 255/45/18 on those wheels.

Originally Posted by stlwagon

+1... 255s are as big as you should go.

Sorry I must disagree with you fine gentlemen.



265/40/18 MT DRs work well, I run them

275/50/18 M&H DRs work well too, they run a tad small and fit well on a 8.5" IMO

There are a few 275/45/18 performance tires that are spec'd to a 8.5" wide wheel, however they are pricey as I recall.

Originally Posted by nielsensmn

Is that the largest for that certain rim? If I buy larger 18' rims for the rear, what would be the largest tire to fit in the wheelwell of that vehicle?

the stock rims are 18x8.5 in size and that's what you need to look at for tire size.

[TheKurgan]

If you want to go wider, I'd have them shipped off to weldcraft. It will be cheaper than buying 4 new wheels. I like the chrome bullitts so if you want to sell your rims let me know

[stlwagon]

Originally Posted by stkjock

Sorry I must disagree with you fine gentlemen.



265/40/18 MT DRs work well, I run them

275/50/18 M&H DRs work well too, they run a tad small and fit well on a 8.5" IMO

There are a few 275/45/18 performance tires that are spec'd to a 8.5" wide wheel, however they are pricey as I recall.



the stock rims are 18x8.5 in size and that's what you need to look at for tire size.

Those are exceptions. Most street tires beyond 255 will have too much sidewall flex which will affect the handling characteristics...

[stkjock]

Originally Posted by stlwagon

Those are exceptions. Most street tires beyond 255 will have too much sidewall flex which will affect the handling characteristics...

maybe, IMO 6 or 8 choices hardly seems an "exception"

Compare Tire Search Results

however the OP asked what's the biggest he can use on the rear of his car. 255s certainly are not the biggest.

[sqidd]

Originally Posted by stkjock

maybe, IMO 6 or 8 choices hardly seems an "exception"

Compare Tire Search Results

however the OP asked what's the biggest he can use on the rear of his car. 255s certainly are not the biggest.

What is the difference between RimWidthRange and Meas.Rim Width? Some of those #'s don't make any sense?

[stkjock]

my understanding (rudimentary as it is) as follows, a tire is spec'd as measured on a standardized size rim, however it will function as designed on a variety of rim width sizes.

[billthecougnut]

I have Goodyear F1's on 18/8.5's that are 275/45/18 and lowered about one inch in back (pro kit springs) I have alot of clearance still, but if you are actually two inches lower in back, it might be a bit tight. I actually posted here (look for "they said these tires would be to big!) on this same question, and got many of the same answers. Just tell the Tire place that This profile IS what you want, they will do it, they just won't reccomend it as a first choice.

I hae plans to buy some FR500 18/9.5 rims in the future, and will transfer these tires to them, the fit shoud be a bit better on those.

Hope this helps. As far as I can tell, 275/45/18 is just about as big as you can go on a 18/8.5 rim.

[sqidd]

Originally Posted by stkjock

my understanding (rudimentary as it is) as follows, a tire is spec'd as measured on a standardized size rim, however it will function as designed on a variety of rim width sizes.

I must have gone cross-eyed when I first looked at those charts. I swear some of them had the Meas.Rim Width outside the RimWidthRange. Wow, I need to get my eyes checked!

[stkjock]

your getting old there sqidd