I am looking to get two rear tires for my 01 vert with stock wheels. My dealership offered me 2 Eagle F1 non run-flats ( I plan to switch to nonrunflats). The tires I have now are standard Kumho 275/40/18 but the Eagle F1 tires are 275/35//18. The service people are telling me that it will perfectly fit and will be just a little wider. Forgive me for my ignorance but this is something that I don't completely understand.
If the tire width on both tires is 275 mm how can the tire with lower aspect ratio be wider? From what I understand the aspect ratio is the % that compares the sidewall height to the width of the tire. Is it correct? So both tires can have the same width but different sidewall height.... in this case, how can one be wider then the other?
Also I would like to know how these Eagle F1 tires compare to others. How much lighter would they be? I am looking for performance mainly and If anybody has these same tires I 'd appreciate some info.
Thanks

 

Your existing tires are the correct size. The dealer's tires are a bit shorter but if you want to know the actual tread width of almost any tire, go to www.tirerack.com. select the tire and go to "specs". Here's an example:
http://www.tirerack.com/tires/tires....=yes&tab=Specs

and Kumho:

http://www.tirerack.com/tires/tires....=yes&tab=Specs

As you can see, the Kumho tread width is a bit wider.

...and here's a page that has links to pages showing you how to determine overall diameter and other calcs:

http://www.tirerack.com/tires/tiretech/tiretech.jsp

 

The tires are not wider, they are shorter. In fact they are 1.1" less diameter. If they are being run with the OEM sized 245-45x17 front, they are too short.

Click here for a tire calculator. You can plug in the stock size on one side and the proposed size on the other - and then compare the two. Notice that the section width is identical on both tires, but the diameter is noticeably different.

As far as the tire is concerned, I believe the Eagle F1 was the OEM tire for the C5 Z06, but not in that size.

 

You are correct; 275 width is 275 width, regardless of the aspect ratio. So...you aren't ignorant, but quite possible the service people at the dealership are. Either that, or they are being deceitful, neither of which bodes well for you dealing with them.

 

Correction...the service people are not "ignorant" just imbecile's

 

Kinda-sorta. If you look at the specs, the goodyear is actually slightly wider overall (sectional width, which is sidewall-to-sidewall) but also slightly narrower (tread width, which is just the tread itself). It really has to do with the shape of the tire, the goodyears have sort of rounded shoulders, so overall they are wider but they have less measurable tread. This is measured with no load of course. Once you put the car on the ground those rounded shoulders are going to flatten out a bit and you can effectively have more tread touching the ground now. Of course, tire pressure can change this too. Plus, having said all that, the differences are quite small anyway.

Point less, tire sizes are kinda like pants sizes. Sure two 275s should be the same width but there is a lot of variance between manufacturers.

However, this does not change the fact that the dealer is an idiot for recommending 275/35/18s and claiming they will be wider (and not even mentioning how much shorter they will be).

The actual problem is that they probably want to sell Goodyear tires (maybe highest profit margin?) but goodyear does not make a 275/40/18 in the F1 so they are trying to sucker you into buying the wrong size.

Furthermore, even if you did go with the 275/35/18 Goodyears, they don't make a suitable front tire size so you'd have mismatched tire brands/model. The closest they have is a 255/45/17 which is taller than 275/35/18. Your front tires would be slightly taller than the rears, making it look dumb and playing havoc with your AH most likely.

In other words, run away!


Dope

 

Thank you for the info, I started my search for a pair of good performance rear tires and I can't make up my mind now because there are so many different kinds ranging anywhere from 150$ to 350$ per tire and I really do not know which brand to trust. I know I want NONrunflats, I know I want 275/40/18, I would like them to be lightweight, have a good grip, and priced around 200$ What kind would you guys recommend? What types have you tried? Which one do you prefer? Why?
Thank you again

 

Hi ignatkor,
Since I see you are in Fl, I'll assume you are looking for a summer tire. There are plenty of decent ones. I've had good luck (as have friends of mine) with the Toyo Proxes T1-R (available from Treadepot), and it seems a lot of folks here have good things to say about the Hankook V12 Evo (from TireRack). Both are in your price range. Try doing a search as your question is not unique.

 

Here is the best tire around. Better then tires that cost twice as much

275/40-18 Hankook V12 Evo K110 and it comes in a 245/45-17. Got a deal going now for &60 rebate on set of 4.

 

You went to your dealer for TIRES? Help!!!

 

Originally I went to the dealer for radiator fan check, asked about tires cause I didn't want to pay for shipping and wanted to see the tires in real life before buying and those were the only tires they had available.
now that I discovered tire rack I will never ask them again

 

Car and Driver Tire Review

http://www.caranddriver.com/reviews/...mparison_tests

 

Very good deal for very nice tires.

I still love my Goodyear GSD3s but alas, they are no longer available in C5 coupe/vert sizes.

 

I hear good things about the Continental
ContiSportContact 3.

Ah here it is: http://www.tirerack.com/tires/tires....SportContact+3





BTW the tread pattern on these is nearly identical to Michelin PS2's but less expensive.

 

Also, many people mistakenly use the "275" as the tread width. It is NOT the tread width, it is the section width of the tire. It is measured at the widest point of the sidewall when the tire is inflated on the recommended rim. If you have two P275 tires they can have different tread widths depending on how "poochie" the sidewalls are designed to be.

To answer the OPs question - stick with stock sizes. The dealer trying to sell you the smaller tires are giving you bad advice.

 

This article will explain calculating tire sizes:

http://www.tirerack.com/tires/tirete...e.jsp?techid=7