With those parameters (7mm spacers, no lowering), the 265 fronts and 305 rears not only fit the wheels but will have fender clearance to spare.

 

 

 

Couldn't fit 305's on the rear with my wheel offsets, but did install 265/30/20's on the front. The tire was about 3/4" wider than my 255/35/20 P zero, but some of that variation appears to be due to manufacturer differences. The lower profile - 30 series vs 35 also is noticeable appearance wise, and I prefer the look, I found the 35 series tire too tall looking. Note that there is a tradeoff on sidewall protection, so if your roads are bad and you are worried about ground clearance already, skip the 30 series and go with 35.

Since I changed both brand and size at the same time, I can't speak to how much of the improvement in handling was due to better tire vs. bigger size, but overall the car carves turns better for sure. Our cars are heavy, and that in my book argues for getting as much rubber on the road as possible. I know there are those that argue wider tires just reduce the other dimension of the contact patch, but I always offer the rebuttal that one rarely sees motorcycle width tires on a car. And for lateral (cornering grip) I believe wider tires help.

 

The 30 or 35 represents the height of the sidewall as a percentage of the tyre width, so 255/35 = 89.25mm, 265/30 = 79.5mm. The rear 295/30 gives a height of 88.5mm so should look about the same as the 255/35. Apologies if I'm teaching granny to suck eggs.

 

Your math appears correct - and this is all pretty subtle, but to my eye the 255/35 (at 89.25mm) already looked at least as tall or taller than the rear 295/30 (88mm), and I figured going to the 265/35 would then increase the height to 92mm, thereby being larger than the rear tire. So I went with the 265/30, which at roughly 80mm helps get the front of the car a tad lower, and makes the front tire at least not look larger than the rear.

Maybe I owned too many hot wheels as a kid, or too many muscle cars in my youth, but I prefer the rear wheels and tires to appear slightly larger than the front. Besides, cars accelerate faster when they are always going downhill

 

 

Well. as previously mentioned, it's a pretty subtle difference. Just need to decide what is important to you.

For the rears, everyone is already using 30 series, and there is no reason to change it.

For the fronts, its basically a 1 cm difference in sidewall height between the 265/30 vs the 265/35. Typically one centimeter means very little, but for example, if you were already frequently scraping the nose on the roads you commonly drive on, then you may not want to get the 30 series since now you may then experience more severe scraping with the front 1 cm lower. Conversely, your car is stock height or mildly lowered, and your roads are good, I doubt you'll have a problem with the 30 series. The other issue is road quality, if you frequently encounter giant potholes or don't typically keep your tires properly inflated, the 35 series gives you a tad more rim protection over large road defects.

 

 

Yes, should work fine, although perhaps someone with AWD should confirm for us.

 

 

I will be replacing my Pzeros shortly and ran the comparison with oem and the 265/35/20 and 305/30/20 just to see the differences; the math looks like this and can be checked by fellow forum members:

OEM FRONT: 255 x .35=89.35 PROPOSED: 265 x .35=92.75 Delta=3.5 mm
OEM REAR: 295 x .35= 88.5 PROPOSED: 305 x .30= 91.5 Delta=3.0 mm

DELTA Front to Rear: OEM = 255 (89.25) to 295 (88.50) = .75 mm x 2; front taller than rear
DELTA Front to Rear: PROP.=265 (92.75) to 305 (91.5) = .75 mm x 2; front taller than rear

 

I make 265 x .30=79.5

 

Typo. Should have been 265x.35. Corrected. Thanks.

 

Regarding:
OEM FRONT: 255 x .35=89.35 PROPOSED: 265 x .35=92.75 Delta = 3.5 cm = 1-3/8"

 

Lucky I called Costco 1.5 hours before my confirmed appointment. Their online appointment center never sent a follow-up notice or text so I got worried.

The guy said they just came in last night, but they just got 'thousands' of tires in and he is not sure he can find them. Assuming Murphy's Law is fully in effect here. Let the fun begin!

 

 

It is I who was confused and now am not. Don't know what I was thinking on the cm vs the mm. Thanks for the heads up there. I've corrected the post accordingly. Doesn't seem like there's any significant difference.

 

Well color me impressed.

They did a great job. Changed my lugs to 17mm for me. Used my black weights. The tech - Stephen is a car enthusiast and really gave my R the treatment, balanced to perfection.

Gotta say I went in very cynical, but left happy.

As for the tires I can already tell a marked improvement in ride quality. A lot less harsh. Can't comment on grip yet. Surely will be better in cold/rain.

Thanks Costco!

 

17 mm lug nuts?
Are you sure?
Stock 19 mm and after-market 21 mm (Toyota & Mitsubishi for example) yes, but not 17 mm.
Never heard of 17 mm in the size and pattern needed for Jags (12 mm x 1.5 mag seat).
Or do you have after-market wheels that take a different style of lug nut, eg. bulge/acorn?