Q45: wheel offsets and tire clearances

[pasadenaQ]

Does anyone else have problems with fits? I am running 18's on my 97 Q and I want a wider set of rubbers. I originally ran Yoko AVS Sport 245/40ZR18's and the tires were awesome! The problems were:1) The tires looked dorky because they were tiny in the wheel well. BUT, I was off-the-line in no time flat because the overall diameter was smaller. 2) The tires wore faster than cheap lipstick on a 2 penny whore. And the tires cost a helluva lot more than 2 pennies each.3) No other Yoko AVS tire size at 18" would clear lock-to-lock in the front.

So, I now am running Pilot Sports. 245x18's in front and 255x18's in the rear. My car is dropped 1" to 1.5" with Eibach springs. The tires clear fine, but they don't handle as well (at least under the weather conditions that are in Los Angeles). The profiles are an inch or so higher and my lost 0-40 times were very noticeable.

Finally, my questions:1) What's the beef with tire manufacturers having different OD's and tread width standards? A Yokoham 9" tread width ain't the same as a Pilot Sport 9" tread width. 2) What is the max limit for front and rear tire size setup. OD, tread width, etc. i.e., what will fit yet still be reasonable enough to spin?3) I understand that Steve Millen ran 18's on his 97-98 Q, and even tested 19's and 20's. Although I know that 18" is the magic number for optimal performance unless you have a slammed race car with rocks for suspension.

Thanks all...

[911/Q45]

Your tires probably wore so badly because the lowered suspension made it impossible to keep alignment camber at a reasonable value. Did the rears wear as badly as the fronts? If you want the look of taller tires and the acceleration of the short ones, perhaps 4.08 differential gears would be the solution.

[AZhitman]

Although I know that 18" is the magic number for optimal performance unless you have a slammed race car with rocks for suspension.

Wrong. 18" is not optimal for performance in ANY category.

Several members here are running lightweight 16x8 alloys with 255/50/16's. THIS appears to be the optimal balance for a Q. 18" rims add unnecessary weight - Looks like going back to the Yoko's would be your best bet (aside from losing the 18's).

Those are gonna wear fast - not only because of your likely alignment issues, but because they're a soft-compound sports tire on a heavy car - Bring that car to Phoenix and those tires would only last HALF as long.

[pasadenaQ]

Hmmm. I appreciate your position AZ. I am simply going by my own personal experience that was initially based upon 3 different articles (with particular reference to a Road&Track "Tech Tid-Bit " article that was full of thought-provoking data). The bottom-line is that the car came stock with 16's and I tested 3 different profile treads that sucked (for me). I had to slam my car to the ground like pimp-mobile and I had too many problems with minor clearances as I drove over the slightest bumps. On the other hand, anything with higher profiles didn't seem to perform as well as the same O.D. 17's. So, I then tried 17's and 18's and the 18's (with similar tire brands, wheel weights, and tire weights) gave significantly better results. Keep in mind that although I researched masses of data, the bottom-line is that I needed to test to see what worked best for my driving style, conditions, and car setup. That being said, more power to the people running 16's out there if it is the "ideal" setup for them. For me, 18's seem to have the best all-around compromise with a weight towards performance (Keeping in mind that the car is 4300 pork-ridden pounds of a luxury vehicle). By the way, my rims are extremely light, but they cost $800 each (big downside).

So, my question should have maybe more clearly and unprovokingly stated :"18's are the ideal for 'my' situation, and does anyone have any wheel/tire experience to suggest a good combo?"

[eQlipse]

What is everyone's opinion on 17" rims from a 1999-2001 touring model?

Also, what about the 18" rims from 2002 on?

[AZhitman]

Gotcha - Thanks pasadena. Incidentally, you mentioned you "had to slam your car to the ground..."

Was this by choice or in pursuit of better handling? Because the Q generally doesn't respond proportionately well (handling-wise) to reduced ride height. Just curious - I'm sure it looks kick-a$$. Post some pics?

18's from a new Q would be a nice swap - Check tirerack.com for available sizes.

You've already tried a tire size that WON'T work - Unfortunately, sounds like you're gonna have to go narrower/taller - in which case you're going to get into trouble with insufficient load ratings.

[pasadenaQ]

Yeah. Thanks AZ. Is it tough keeping keeping your inbound air cool in the summers? I agree about the slamming stuff being not-so-great for Q's. They really weren't meant to be road sleds. I only did to test the limits and see what I had to do to make things fit/perform for the various tire sizes. I could probably go a bit wider in the rear from my 255x45's, but the fronts are mighty tight at 245x45's. The slightly lower profile Yoko 245/40ZR18's were even wider, but the profile was just a tad too short for such a heavy front end. I know that the new Q's come stock with 18's, but I am not sure the actual tread OD and width. I'll keep testing...

[AZhitman]

but the fronts are mighty tight at 245x45's. The slightly lower profile Yoko 245/40ZR18's were even wider

Shouldn't have been enough to notice. The only difference SHOULD have been the sidewall height being 5% less. 245mm is 245mm regardless of brand. (or is this the inter-brand variation you referenced in your first post?)

Interesting quandry - I can't think of an easy (or cheap) solution.

[97Q45t]

PasadenaQ, I plan to put the 18x9 wheels and 275/35/18 in to the rear of my Q45t. Do you think there will be any problem?

[BadQ45t]

Wow, that's huge for the rear, have you had a tire place take a look to see if that kind of rubber will fit? I'm going to get 255 all around on 17x7.5 rims, didn't think anything more would fit. With only 35 series that is going to be a bumpy ride.

[97Q45t]

According to my calculation, the new tires (275/35/18 with 18x9 35mm offset) will be 50mm wider than my original 215/60/16s. The inner sides need 20mm clearance while the outer sides need 30mm to clear the new tires.

Anyone have 235/55/16s or 255/50/16s on 16x7 factory wheels? How would they look?

[AZhitman]

Heath has 255/50s, i have 245/50s, both on factory rims. They look fantastic - See Member's Rides....

[Q451990]

Heath has 255/50s

Sadly, I don't... they're the factory size for the 97-01 Q (215/60/16) but they're getting old - so that will change... don't get me wrong, I've gotten good wear and service out of them but with the 94V rating slightly under the factory recommendation, I think I need to go a little larger this time.

Heath

[AZhitman]

Sory Heath - I got you mixed up with Glenn.