chowder

Is it ok to put on 245/40 tires instead of the stock 235/45? What, if any, are the negative implications?

Next, I'm all over the map with tire choices:
1) pricey all season Michelin Pilot A/S
2) less pricey all season Dunlop SP5000, Yokohama AVSdb
3) Toyo Proxes T1-S
4) cheapo summer Kuhmo Ecsta 712
Any especially favorable, or unfavorable, feedback you'd care to pass along regarding these?

Thanks.

MGS4

Someone here has 255/40 rear and 235/45 front set up on the stock 17'. Maybe you could consider that combo.

Johnny Mo

I wouldn't do 245/40 I'd do 245/45 I have 245/45 on stock size 17X8 rims, check with the tirerack.

Shogun

I've been researching the same question and here's what I've found...

On Stock Rims:

Nothing bigger than 245/45/17 will fit on the front.

For the rears: someone has 265/40/17 (diameter matches nicely with 245/45/17) and reports that they fit just fine - but with a little bulge.

The tire rack also recommends 265/45/17 as optional rear tires on the 17" 8" wide after-market rims that they sell for the GS4.

You can do 245/40/17 but the overall diameter of the tire is smaller than that of the 235/45/17, so unless you want a smaller looking wheel don't go with the 245/40s. The plus side of a smaller wheel is faster acceleration.

That's it for now...

Good Luck,
Eric

HDDuece

Chowder, Go to suspension and handling section and look for widest 17" tire for stock rims and there are pictures of 265-40 on the rear on stock rims.

GS400_PUSHER

I have 255/45/17s on my rears and its fine. Had them on for at least 4 months (no problems).

chowder

Thanks for the replies.

Johnny, see if this makes any sense to you. I'm just parroting what my reputable tire shop guy is telling me.
First he tells me that while something staggered like the 235/45 front + 265/40 rear combo may be level, it isn't too good because a) you may hang yourself when the rears let go and b) you can't rotate properly.
Second, he has a souped up GS4 (mine is stock), and has settled on the 245/40 over the 245/45 because a) the seeming smallness of the 40s is lessened by the fact that they are being sqeezed onto an 8" rim instead of the 8.5" spec, and b) because the taller 45s will lessen response (stiffer).
Any thoughts on his opinions? He's been pretty convincing. He is willing to give me anything from ordinary 235/45 all-around, through the gamut. He's just telling me what has personally worked best for him.

Johnny Mo

As far as the 265's go, unless you are putting down more HP than stock, it'll actually slow you down, more traction/contact patch/friction than necessary. He may be right as far as the whole stagger thing goes, but what really screws you is the fact that you'll need to pick a size for the spare, probably the smaller size. If there is an overall diameter difference when you use the spare on the rear, it is not recommended to do so for an extended period as it will do damage to the differential. Secondly, you will not be able to rotate your tires, which we all know when you up them to the 17" + they tend to wear quickly, so rotating helps squeak a few thousand more miles out of a set of tires.

I actually went with the 245 from the TIRERACK, because the 235's were out of stock. However, I am glad that I did because the roads in NY punish cars and rims daily, the extra sidewall helps in that regard, and coupled with my L-Tuned suspension I have no issues at all with the handling and performance.

All that being said, I am sorry I went with 17" and wish I had done 18"...I have 17" on my Expedition for cryin out loud, how embarasssing for my GS is that! j/k.