: What do you think about this tire combination



slow35th
02-13-05, 01:34 PM
When it comes time to replace my tires I am thinking about running 275 40 18's in the rear and 245 45 18's up front. I think you could get away with this on the 8.5 inch rims as it is only .5 inches shy of the recommended minimum for the 275 40 18. This is the same rolling diameter and there are several makes in this size combination. The goodyear G3's and the Toyo T1-S's both come in this size combination. I know that you would give up the ability to rotate but that is the case on several vehicles anyway including my SRX. Is anyone running this combo?

Lance

StealthV
02-13-05, 04:01 PM
Mmm...275s. Be the ginuea pig!

thebigjimsho
02-13-05, 06:33 PM
You are in virgin territory here. I'm not sure what will happen to handling. You could say you will gain a bit of understeer. But, with the same width wheels, you will have a little less control in the rear because of the angle of sidewall to rim. So, would that little bit of control loss mean that you won't have as much understeer as if you had a wider wheel in back? Or would that really change everything. I'm not sure.

Let us know.

wildwhl
03-24-05, 09:17 PM
The Maggie is insisting that I try this :)

CTSV05
03-24-05, 09:50 PM
Just so I'm clear, the overall diameter is the same, so the only difference is the tire is wider?

Is this correct.

So if that is the case, your sidewall will react differently, due to the tire needing to bulge in the sidewall, to squeeze onto the rim.

Then if thats correct, won't you lose some tread contact on the edges of the wider tire?

slow35th
03-24-05, 09:57 PM
Recomended rim width for the 275 40 18 is 9 inches. Our rims are 8.5 inches. I think you could get away with it. My SRX came with a similar tire combination on the same size rims. My only concern when I made the original post was whether or not the wider tire would have clearance in the rear.

slow35th
03-24-05, 10:10 PM
Here is a comparison of dimensions. 275's on top

Section Width: 10.82 in 275 mm
Section Width: 9.64 in 245 mm

Rim Diameter: 18 in 457.2 mm
RimDiameter: 18 in 457.2 mm

Rim Width Range: 9 - 11 in
Rim Width Range: 7.5 - 9 in

Overall Diameter: 26.66 in 677.16 mm
Overall Diameter: 26.68 in 677.67 mm

Sidewall Height: 4.33 in 109.98 mm
Sidewall Height: 4.34 in 110.23 mm

Radius: 13.33 in 338.58 mm
Radius: 13.34 in 338.83 mm

Circumference: 83.75 in 2127.2 mm
Circumference: 83.81 in 2128.7 mm

Revs per Mile: 780.1
Revs per Mile: 779.6

Speedometer1: 60 mph 100 km/h
Speedometer2: 59.9 mph 99.9 km/h

CTSV05
03-24-05, 11:59 PM
Well, it shouldn't be a problem, but I still think you'll lose some of the "flatness" of the contact patch, but it can't be much.

V-lociity
03-25-05, 11:06 PM
Just my untested and well researched opinion. If you replace the "OE" tire with a non factory tire make sure that you
1: meet or exceed the service rating of the OE tire (in the case of the Goodyear Eagle F1 Supercar 1565 lbs. @168 mph.)
2: If you decide not to follow the recommended rim width guidlines realize that the tires ability to handle cornering loads can change non-linearly making it possible to damage the structure of the tires carcass and possibly unseat a bead etc..
food for thought?

globed70
03-26-05, 10:33 AM
Other than looks or bragging, I don't think there is much to be gained from mounting a wider tire under the minimum width. A properly fitting 245 has to be a better answer than an odd fitting 275. So what is the reason?

wildwhl
03-26-05, 12:32 PM
Looks, partly, but I was hoping for a larger contact patch (guess I'll have to rethink wider rear wheels first) :)

urbanski
03-26-05, 12:59 PM
Looks, partly, but I was hoping for a larger contact patch (guess I'll have to rethink wider rear wheels first) :)
19" HRE C20s are calling your name :D:D
http://www.daemonmotorsports.com/category.php?id=42869635

StealthV
03-26-05, 04:55 PM
Come on Urb, 841Rs (http://www.daemonmotorsports.com/item.php?cid=12235954&id=77352697) ! :coolgleam

http://www.daemonmotorsports.com/images/items/big/wheel_841r-a.gif

urbanski
03-26-05, 05:28 PM
Come on Urb, 841Rs (http://www.daemonmotorsports.com/item.php?cid=12235954&id=77352697) ! :coolgleam

http://www.daemonmotorsports.com/images/items/big/wheel_841r-a.gif
:D
I'll use the grand I'm saving with the Comp series to buy, er, stuff, like CTSV05's AH kit, maybe a shifter, and the downpayment on the head/cam package :p :D

slow35th
03-26-05, 06:03 PM
Just my untested and well researched opinion. If you replace the "OE" tire with a non factory tire make sure that you
1: meet or exceed the service rating of the OE tire (in the case of the Goodyear Eagle F1 Supercar 1565 lbs. @168 mph.)
2: If you decide not to follow the recommended rim width guidlines realize that the tires ability to handle cornering loads can change non-linearly making it possible to damage the structure of the tires carcass and possibly unseat a bead etc..
food for thought?

Item 1. All of the tires we are talking about here are Y or z rated tires.

Item 2. I would agree with you if we were talking about 1 or 2 inches below recomended rim width but half an inch is not likely to change the contact patch or handling characteristics of any significances on a 40 series tire.

Dreamin
03-27-05, 02:55 AM
Whl: running a 275 on the stock rim will only increase contact patch width a neglible amount. You wont feel a difference traction-wise. But with the power you're putting down... the extra sidewall bulge may make the rear feel "squirmy" / "squirrely".

Get the widest rear wheels you can and tires that match that wheel size... CCW 19x10 for example.

globed70
03-27-05, 10:27 AM
I'm thinking you will change the shape of the contact patch but not the overall size... the shape change may support more lateral grip, but I'm not convinced it will give you added acceleration grip if properly inflated. Just my 2 cents.

wildwhl
03-27-05, 12:37 PM
Thanks everyone for the input.

Dreamin, I tend to agree with you, but I still feel the stock rims look the best of any that I've seen on the V. What I REALLY want is a stock wheel widened to 9.5 or 10" and I know we've discussed this before. It can be done, the question is whether it is worth the expense.

I have some time to decide, as I have a total of 10 245/45/18 tires with good tread at the moment (6 F1's and 4 GSD3's). Likely won't happen until next winter when the winter set goes on - but - still want to figure it out in the meantime.

If we could only find away to get 50-100 stock wheels widened for under $200 per wheel then we could do a GP and get going :)

V-lociity
03-31-05, 01:36 AM
Slow35th, In point one I'm not concerned with the "speed rating" but the load index should be considered critical on a car that weighs 4000 lbs + with driver/passengers. If the car is driven at high cornering speeds (that's one reason I bought mine) 1/2 inch more width can actually have a adverse effect on tread wear at a minimum, possibly less traction that your getting now, I checked Toyo's website and the service description/load index for the T1S exceeds the OE tire when mounted on a 9.5" wheel but you would have to find out from Toyo engineering how much that would change on an 8.5" wheel. I'd bet any warrantee is void for sure. I have never driven a mile on a Toyo, I spend most my time on Kumho V710's, Hoosier R3S03's, R3S04's, If you talk to Toyo I'd be interested to know what they say.
Toy customer service: 1-800-442-8696