Spring is right around the corner and it's time to ditch the horribly vague feeling winter tires.

I'm thinking of fitting a set with larger overall diameter, going from 27'' front and rear, to 27.6'' front and 28''.7 rear.
Have anyone done something similar and is there any adverse effect of doing so?

My main concern would be issue with the nannies, since front and back would be rotating at different speed, fitment might also be a concern on the rear with 1.7'' increase in diameter.
Speedo calibration is less of a concern since my seating position blocks the entire 50-120mph range anyways

My main goal with this set up is to widen the tire width, stay at 20'' rims, fill in the wheel well without lowering the car, and increased comfort due the higher sidewall.

the change will be

front
original 9'' width rim 255 35 20, 27'' diameter
new 10'' width rim 275 35 20, 27.6'' diameter

rear
original 10.5'' width rim 295 30 20, 27'' diameter
new 11.5'' width rim 315 35 20, 28.7'' diameter

Please lemme know if this is a good idea!

 

I'm given to understand you're going to be hard pressed to fit a 315 rear tire. I imagine it will be even worse with that much higher profile of a tire. Why would you want a HIGHER profile tire anyway? That's a little bit of a muscle car look. If you'd like to go higher diameter, I'd at least keep the same profile and go with a 21" wheel (which is my plan for spring)

 

From a few Michilen 4S and Cup 2 trial and errors on my V8 S, a 15 R, and a 17 SVR, the only remaining candidate for the best summer tire is the R888R. It only ships in a 315 so thats why I'll be running it soon. My current 4S 305s look better than the stock 295s with no fitment or nanny issues, so its not a crazy idea IMO.

 

Should be no problem as long as you select the proper offsets for the wheels and have an RWD. However, the front/rear tire diameter differential would be to much for an AWD.

 

The R888Rs are a great choice. I have then in 325s on my C7 Z06 and they hook like a boss! The F Type doesn't really need it being AWD, but they stick in the corners too. Unfortunately they don't come in 21s so they're out for me on the F Type. Do let me know how those 315s work out for you as far as rubbing and fitment. I'm quite curious

 

My friend just pointed out the car will be 1.7'' higher off the ground on the rear, I don't know if that's gonna be a good look haha. I can also go for 275 40 20 in the front and the entire car will be 1.7'' higher off the ground, and that'd make front and rear diameter match.

@Toddiesel I'm avoiding 21'' since the road here in nyc is not what you'd call good. stock setup has 3.5inch of side wall, I'd like it to be a bit thicker.

@Unhingd Yes the car is RWD, I will have the wheels custom made so offset shouldn't be a problem, if memory serves me right, our car can handle quiet a bit more aggressive offset, but i'm going wider so I will do it somewhat conservatively, like 40 front and 30rear.

for tires I think ps4s should serve me right, as I don't plan on tracking the car, mostly highway cruising and back road ripping.

 

@Ray Ray I don't think roads anywhere are "good". Seems like that's a massive complaint for anyone who cares about their car. Since you're getting custom wheels, that generally means forged and those things are far stronger than cast wheels, so there's less concern about bending and certainly less concern for cracking. Basically just avoid potholes. The struggle is definitely real, but you can't let that get in the way of what you like. If you prefer the higher side wall, that's certainly your prerogative and will be a unique look. If you're just getting high sidewalls cuz you're skrud though... don't be skurd! ;-)

 

Will do. I have 560 WHP in RWD and my 4Ss are overwhemled. A friend with an AWD SVR talked me out of Cup 2s after not being happy with them.

 

https://www.discounttire.com/learn/tire-size-calculator
315/30s are 0.48" taller and 0.79" wider than 295s. So the rear end would rise 0.24".

 

Oh dude, the Cup 2s are crap. Just check out the C7 Z06 forum and anyone will tell you that. Apparently they're not even good for track days. And yeah, if yours is RWD, the R888Rs are THE best, imo. 560 is about what the Z06 has stock at the wheels, maybe a tad lower, and stock I couldn't hook on the PSSs or the Cup 2s to save my life. The R888Rs, I have to legit try to break em loose. Just look at this video. Where I do a burnout, I revved to redline and dumped the clutch and that was the biggest burnout I could get before they hooked (around 45 seconds into the video)
TOTALLY not trying to be snarky but if they're .48" taller, wouldn't the rear end rise .48"?

EDIT: Nope, I'm dumb, it would obviously only raise half the tire, duh. Realized it as soon as I hit submit

 

Yes they will be stronger being forged but also harder to replace when things do happen, I bent and cracked quiet a few rims on my previous car and they were only 18s albeit similar(if not exactly the same) sidewall height.

I'm not sure if I will like the look, especially after my friend pointed out it will make the car sit higher, 1.7'' is huge as I remember my previous 328 was lower by around that amount and it made the car look so much lower visually, I'd hate to spend 1.6k AND ruin the look of the car.

That being said you probably guessed I'ma stick with the oem spec, tires are cheaper and it is tried and true. Here is a thread I found that swayed my thoughts, a lot good info worth a read.

https://www.jaguarforums.com/forum/f...-152064/page2/


Edit: @Toddiesel just realized I made the same mistake haha, car should be raised by 0.85'' instead of 1.7'', still not a small amount though, considering the F type is not a low car to begin with.

 

If you’re looking to reduce wheel spin, you want a taller tire and lower air pressure. Don’t worry about tire width, because that won’t help you.

 

While a taller tire with lower air pressure will provide a much larger contact patch than just a wider tire, you shouldn't be driving around with 20 psi in your tire. For the street, wider is the only feasible option (and a stickier tire of course, like the R888R). And if you're just talking the track, why bother with lowering air pressure? Just get some DRs or better yet, wrinkle walls.

 

A wider tire provides 0% larger contact patch than the tire it’s replacing, because that’s how physics works. P = F/A. If your tire pressure is the same, and gravity/the mass of your car is the same, the contact patch will not increase in size. You’ll only change its shape, and in this case to a negative effect for wheel spin reduction.

 

Meanwhile, wider just looks cooler and you know it!

 

It does... but it also can ruin your car.

 

Sure, I'll bite. How is that?

 

If you put inappropriately sized wheels/tires on your car you can absolutely ruin the handling characteristics or ride quality of the vehicle. Sometimes both at the same time.

 

Ehhhhh... if it fits in the wheel well, you're fine. If you're doing something like this, sure.

 

"if it fits in the wheel well, you're fine" is exactly how people screw stuff up. People don't consider the amount of engineering that goes into things like wheel/tire selection, spring rates/dampening, bushing durometer, etc. They think to improve performance, you automatically have to go wider and stiffer, throw parts at their car and completely ruin it.