I have 32K miles on my 2014 GT/CS and at the oil change I was told two of my tires are toast and other two aren't far behind.

I'd like to go with 255's and I saw 255/40/19's on a new 2015 GT at the dealership that looked good but I'm concerned that they are 27" tall vs. the stock tires 27.7" tall for the 245/45/19's

Will I notice the 0.7" less height? I know, I know, "That's what she said"

I assume this will increase the tire to wheel well gap by 0.35"? Am I thinking that through correctly?

I'd really like to go with 275/40/19's but they wont fit the stock 8.5" wide GT/CS wheels and wheels and tires are NOT in the budget right now.

What do you guys think?

 

If the new tires have less height then the new tires will be farther away from the wheel well so you will have more gap. If you have 3.73 in the rear I would go with a taller tire. That will also close the wheel well gap. There will be sales soon for wheels if you can wait a bit.

 

255/40 19



275/40 19




And before I had the 9 inch wheels I was running the 275's on the 8.5 wheels

 

Ken, how wide are the wheels in those pics? What 275 tire were you running on the 8.5" wide wheels ?

 

its a vert so no 3.73's. I can't recall what came on the vert, 3:31?

 

The top is the 8.5, bottom is 9.0.
Continental DW's and the weren't bulged out

Actually 3.15 is the gear for a GT Vert

 

I was running a 255/40/19 on my stock wheels 19x8.5. Stock tires were 245/45/19. They worked great. By the time I had done this I had already lowered my car, and I didnt notice the .7 inch difference.

 

For 2014 3:31 was standard on GT and 3:55 and 3:73 was optional

 

For some reason I was thinking Auto

 

If you want to stick with original diameter, did you consider the 275 35 19? It puts more tire on the ground, but is closer the diameter of the stock 245 45 19's.

 

I think you have a typo. 275/35 is 26.59" tall, so it's further away from 255/40 which is 27"

OP, You won't notice much of a difference going 255/40-19. With 3.31s the impact will be better acceleration actually. It's like going from 3.31 to 3.40 or so due to less radius.

with 3.73s this tire (and thus the gearing) is a bit short, but ****, the acceleration is awesome!

 

The 275 40 19 is closer to the diameter of your original 245 45 19's, but may be a little wide for your stock wheels. Most manufacturers minimum wheel width for the 275's is 9 inches.

 

Spot on!


I run my 275/40s on 19x9.5 as that is the measured size, but you can run it on a 19x9 and sacrifice a bit of contact patch and sidewall stiffness.

 

My mistake, I was thinking about the 275 35 19 being close to the same height as the 255 40 19, which is what my car came with. I tried to go back and correct the post, but you caught the error first.

 

No worries bud. The community here is sharp, and other have caught my own mistakes more than once.

 

I had the 255's and was looking at options the last couple of weeks. I looked at both the 275 35 19 and the 275 40 19. I got the numbers mixed up in my first post. I should no better than to post from memory. I ended up with a set of Bridgestone S04's in 275 40 19 on my stock Brembo wheels (19x9). I had two mounted up last week and put on the rear since I couldn't fit all four in the trunk at once. This results in a staggered set up with 255 40 19's on the front. This measure out to about a .7 inch difference in tire size front to rear For the OP, looking at the car from the side the difference is not really noticeable. From the rear with the car quartered away and the front tires turned to expose the tread, the added width is noticeable. Like 5.Monster said, the overall gear ratio will change slightly. For me this means a slight loss in acceleration, due to .7 inch increase in diameter. I don't really notice it when driving, but I am sure it is there. Also, the 255's feel a little more harsh on highway seams/pot holes, although this may be due to being a different brand, than the change in sidewall height. I hope this helps.

 

If others are reading this and considering 2015-16 wheels and tires, like I bought, the tpms sensors won't register on an older mustang. Mines a 2014.