245/40/18 on a 2003 Q45?

[DuDro]

I thought that this was answered for me in the past, but I cannot locate the original thread....

Does anyone know if this size will be suitable for my 2003 Q45? Please advise. Thanks!

[Falkdesigns]

What size wheels? That size tire will work, but I wouldn't put them on a wheel narrower than 9", you'd probably be Ok on an 8", but it will look nicer on a 9". I have that size on 9" rear wheels, but mines a '98.

[DuDro]

I will be using my stock wheels. I believe they are 7.5" wide and 18" in diameter....

[Falkdesigns]

Well, honestly that's kinda wide for a 7.5" wheel, I'd suggest 225/45 or 235/45 for that wheel (if it was me, I'd get 225/45 for a 7.5" wheel).

[AZhitman]

I disagree with Kevin...

I have 255/40/18 on 18x8's and the sidewalls are nearly perfectly vertical.

See pics in Member's Rides.

245/40/18 is fine on a 7.5" wheel.

[DuDro]

The OE Michelins are 245/45/18s...

I just wanted to make sure that the 0.48" decrease in sidewall height would not be too drastic for the rim and the overall size of the car.

Thanks for the input....

[Falkdesigns]

This is where it just comes down to taste, and I like the wheels to be wider than the tires. I'm not a fan of extremely stretched tires, but I like the side walls tilting in a bit, slightly stretched.

[maxnix]

The OE Michelins are 245/45/18s...

I just wanted to make sure that the 0.48" decrease in sidewall height would not be too drastic for the rim and the overall size of the car.

Thanks for the input....

I disagree with both AZhitman (7.5" rim width is too narrow for that width of tire with that aspect ratio) and Kevin.

This is where it just comes down to taste, and I like the wheels to be wider than the tires. I'm not a fan of extremely stretched tires, but I like the side walls tilting in a bit, slightly stretched.

Tire sidewalls should be vertical or only slightly less for best performance, not[ stretched at all. Check the yokohama and TR websites for fitment information. I would stick to 245/45-18 on 8", but especially 7.5" width rims.

[Falkdesigns]

I want mine to be on the widest end of recomended wheel width for a particular tire width. I have 245 on a 9" wheel which is well within the recomended width and sidewalls are tilted in. The weels I'm getting are 9 f and 10 r, but I plan on running the same size tires I have now, 235 & 245.

[maxnix]

I want mine to be on the widest end of recomended wheel width for a particular tire width. I have 245 on a 9" wheel which is well within the recomended width and sidewalls are tilted in. The weels I'm getting are 9 f and 10 r, but I plan on running the same size tires I have now, 235 & 245.

Very nice!

I'd say ithe sidewall is vertical. Recommended rim width on 245/40-18 at TR is 8"-9.5"

245mm = ~9.65"

Hope you are running XL load rated versions, as normal Michelin PS2 in those sizes are load rated at 91 and 93, whereas minimum OEM is 94.

Don't know why anyone would want to reduce braking performance and increase understeer by running a smaller (less load rated) tire on the heavier front end of any Q45.

[Jeff Williams]

I ran 245/40/18's on my ASA Revolutions (8" wide), because that is what where on the rims when I bought them. The load rating was a 93, which made me nervous. The ride was fairly harsh on uneven pavement.

Now I have 245/45/18's and the ride is phenominal. The speedo is off about 2 MPH at 80 (according to my GPS tracking system).

I would say, go ahead, but you will be more happy with the 245's.

[szh]

I'd have to agree with the comments that say "go/stick with the 245/45-18" size. They are available in the right load index, and the 7.5" width is the minimum for that size, so it should work fine.

If I was going to violate the min rim width rule for a particular tire, and I don't recommend it, then I would not be off by more than 0.5". FWIW, I are very concerned about Greg's rim/tire choice ... for safety reasons!

[szh]

Now I have 245/45/18's and the ride is phenominal. The speedo is off about 2 MPH at 80 (according to my GPS tracking system).

True for your older Q, but DuDro has a 2003 Q45, whose stock tire size was 245/45-18, so his speedo would not be off!

Quote »I would say, go ahead, but you will be more happy with the 245's.[/quote]I agree most strongly!

Z

[Falkdesigns]

Hope you are running XL load rated versions, as normal Michelin PS2 in those sizes are load rated at 91 and 93, whereas minimum OEM is 94.

My tires are Nankang NSII, (see tire thread sticky) 235/40-18f, 245/40-18r, 95f and 97r load indexes, 45psiF, 42psiR. Over one year on them now, perfectly even wear (even with 2" drop), quiet, comfy, excellent traction wet and dry.

[DuDro]

Thanks for all the input!

I am considering new tires because the OE Michelin Pilot MXM4 tires are....how should I say this tastefully...CRAAAAP!!!

I can't believe that Infiniti would use these tires as originial equipment on their $62K flagship sedan.

I want to be better prepared for the DC-area winter weather, so I found a set of Michelin Pilot Sport A/S tires on eBay for an incredible price! The size of the tires are 245/40/18s.

All the reviews for the Michelin Pilot Sport A/S are outstanding and I am eager to get these on my car. The only downside is the price, which will be close to $1,100 with shipping.

I guess I will need to decide whether it's worth sacrificing the difference in ride going from a 245/45 to a 245/40.....

Sometimes it really sucks that I am so cheap

[DuDro]

All the reviews for the Michelin Pilot Sport A/S are outstanding and I am eager to get these on my car. The only downside is the price, which will be close to $1,100 with shipping.

I need to clarify that the set of tires on eBay have ~ 3K miles are selling for more than half the price of the new set, which are $1,100 from Tire Rack...

[szh]

I am considering new tires because the OE Michelin Pilot MXM4 tires are....how should I say this tastefully...CRAAAAP!!!

Agreed!

I want to be better prepared for the DC-area winter weather, so I found a set of Michelin Pilot Sport A/S tires on eBay for an incredible price! The size of the tires are 245/40/18s.

Hmmm ... some eBay deals may not be worth the money. Are they new? Is is a reputable dealer, etc.?

EDIT: okay, I missed your last post. I am concerned that this may be a situation of "penny-wise, pound-foolish". Tires are not a place where I would be worrying about. Like I say below, if price is an issue, I'd get another less expensive brand rather than the wrong size/load index tire!

All the reviews for the Michelin Pilot Sport A/S are outstanding and I am eager to get these on my car. The only downside is the price, which will be close to $1,100 with shipping.

I guess I will need to decide whether it's worth sacrificing the difference in ride going from a 245/45 to a 245/40.....

Yes! They are expensive tires for sure. . I suggest that you consider one of the other A/S tires if price is a concern - like the Avon Tech M550 in a 245/45-18 size.

I have not lived in Washington, so I cannot comment on the weather there. Does it get snow much? That hangs around? If so, then you may be far better off by getting a set of cheapie wheels and true snow tires for the Winter months!

Z

[maxnix]

I want to be better prepared for the DC-area winter weather, so I found a set of Michelin Pilot Sport A/S tires on eBay for an incredible price! The size of the tires are 245/40/18s.

All the reviews for the Michelin Pilot Sport A/S are outstanding and I am eager to get these on my car. The only downside is the price, which will be close to $1,100 with shipping.

The Pilot AS, like any all season, is a serious compromise.

The PS2 are the ones everyone rates so highly, but a no go in the snow, as any good tire is that is not a winter tire.

[AZhitman]

Don't fret too much over my fitments - Remember I have the 8" wide Premiums (which we've beaten into Horse Heaven).

See pic:

Dennis = 255/50/16 on 8" Z rims.Greg = 255/40/18 on 8" Q rims.

Be advised that the "recommended range" charts are developed for the proletariat BY nimrod attorneys and other non-car people.

Besides, if you look at the upper rim width range of some of these tire sizes, you're not only stretching tires but you're also playing AT or below the recommended load range for a given car.

[Jeff Williams]

Don't fret too much over my fitments - Remember I have the 8" wide Premiums (which we've beaten into Horse Heaven).

Are you SURE those aren't 7.5" wide? You know, you are supposed to measure from bead surface to bead surface, not outer rim dimensions.

Hey guys, remember, as the sidewall gets shorter, the angle of the sidewall becomes greater, when you have differences in tire and rim width. Theoretically, if you have a 295 MM width tire, it would fit on a 7.5" wide rim, if the sidewall was high enough.

[AZhitman]

Yes, they're 8". We've been there before. '04 Premiums were 8".

[Jeff Williams]

I'm gonna have to ask you to un-mount a tire, and take a picture with a ruler to prove it.

I love deceased equine bashing!

[maxnix]

Are you SURE those aren't 7.5" wide? You know, you are supposed to measure from bead surface to bead surface, not outer rim dimensions.

Hey guys, remember, as the sidewall gets shorter, the angle of the sidewall becomes greater, when you have differences in tire and rim width. Theoretically, if you have a 295 MM width tire, it would fit on a 7.5" wide rim, if the sidewall was high enough.

So true.

I remember the rear Z32 rims being 16x8.5. I'll check with Joe next time.

Far as I can tell, the 255/40 on Greg's 18x8 (OEM chromed and first offered only on the 04 Premium) rims look fine, and the 255/50 on his 16x7 didn't look pinched. In fact, on the Yokohama site, they cite that as the minimum wheel rim width for that size in 16".

They also say in lower profiles, the wheel width is optimal if it is 90% of the tire section width.