HRE 543R: Testing clearances on 2007 XLR

[Phrede]

You do not want the tire to stick outside the fender. You would be asking for trouble. When I put the new wheels on the x they fit right at the edge. It was no problem until we went on a trip and filled the trunk with more weight. I heard a slight rub every once in a while. Very little. When I finally checked it it had almost rubbed through the fender. Fortunately I caught it in time. I ended up raising the ride hight screws an inch and haven't had a problem since. But I sure wouldn't want any more width in case there was a bad dip in the road at high speed.

My personal preference is that tires belong inside the wheel well for a number of reasons. Not everyone agrees. I would not go to less than a 35 series either and prefer a 40 series. The beauty of this car is the balance of style, comfort and performance. If I wanted a super stiff ride / full out performance car it would not be the XLR.

 

[Popbigguy]

Sometimes it seems no one believes me when I say offset is everything when it comes to what will or will not fit. You could put a 500mm wide tire on the rear with the right wheel and offset. Yes, it would stick outside the wheel wells but would work.

A stock V wheel is 8.5 inches wide with a 61mm offset. The placement of the outside edge of the rim relative to stock is simple mathematics.

If the stock rim is .5" inside the fender a 10" wide rim with a 49mm offset would be 1.22" different from stock and stick outside the fender by .72". If it will clear on the inside is another story. Things get a lot tricker on the front due to steering angles etc.

The bottom line is to say "I fit an X wide wheel on my car is not enough information without including the offset.

Where do you get the 1.22" difference? 61mm - 49mm = 12mm, mm's X .03937 = inches. So,,, 12mm X .03937 = .47". Did I miss something? (wouldn't be the first time!). I got to buy tires coming up to soon! So I been checking these posts out.


Edit!!! Oh Duh!!! 10 over a 8.5 rim.

 

[madcurl]

Sorry guys, but I'm on vacation and haven't tried the wheel on the rear.

Meanwhile, here's a few pics from the trip to Napa via San Francisco, CA.

 

[madcurl]

Sometimes it seems no one believes me when I say offset is everything when it comes to what will or will not fit. You could put a 500mm wide tire on the rear with the right wheel and offset. Yes, it would stick outside the wheel wells but would work.

A stock V wheel is 8.5 inches wide with a 61mm offset. The placement of the outside edge of the rim relative to stock is simple mathematics.

If the stock rim is .5" inside the fender a 10" wide rim with a 49mm offset would be 1.22" different from stock and stick outside the fender by .72". If it will clear on the inside is another story. Things get a lot tricker on the front due to steering angles etc.

The bottom line is to say "I fit an X wide wheel on my car is not enough information without including the offset.

True. The original offsets were: 52ET (front) and 61ET (rear). However, this is a 3-piece wheel thus a lot more options vs a OEM wheel using a set offset or for that matter a 1 or 2-piece wheel. The pad height, the inner and outer barrels all play a part in customizing the positioning of the wheel, brake clearances, back/front spacing, and the deep of the wheel and/or outer lip . I have all of the specs, but didn't want to muddy the waters since some of those specs were used as a base point. I was working (originally) with the lead guy at HRE who was using other XLR applications and then adding or deleting the desired setting I wanted.

 

[madcurl]

My personal preference is that tires belong inside the wheel well for a number of reasons. Not everyone agrees. I would not go to less than a 35 series either and prefer a 40 series. The beauty of this car is the balance of style, comfort and performance. If I wanted a super stiff ride / full out performance car it would not be the XLR.

Agreed. 35-series is perhaps the most extreme route I would go with on a XLR using after market wheels. As you know, going 35-series is used because of the increase in wheel size and keeping the same diameter. Granted, comfort takes a back seat.

 

[madcurl]

You do not want the tire to stick outside the fender. You would be asking for trouble. When I put the new wheels on the x they fit right at the edge. It was no problem until we went on a trip and filled the trunk with more weight. I heard a slight rub every once in a while. Very little. When I finally checked it it had almost rubbed through the fender. Fortunately I caught it in time. I ended up raising the ride hight screws an inch and haven't had a problem since. But I sure wouldn't want any more width in case there was a bad dip in the road at high speed.

Thanks. I may have to perform that same task. Traveling through San Francisco this past week I encountered plenty of road issues. Anyway, keep um' coming! I like hearing what others have done for I've only had the XLR since May of 2013.

 

[Phrede]

Where do you get the 1.22" difference? 61mm - 49mm = 12mm, mm's X .03937 = inches. So,,, 12mm X .03937 = .47". Did I miss something? (wouldn't be the first time!). I got to buy tires coming up to soon! So I been checking these posts out.


Edit!!! Oh Duh!!! 10 over a 8.5 rim.

Don't you hate when that happens I know you understand exactly what I'm talking about.

 

[Phrede]

True. The original offsets were: 52ET (front) and 61ET (rear). However, this is a 3-piece wheel thus a lot more options vs a OEM wheel using a set offset or for that matter a 1 or 2-piece wheel. The pad height, the inner and outer barrels all play a part in customizing the positioning of the wheel, brake clearances, back/front spacing, and the deep of the wheel and/or outer lip . I have all of the specs, but didn't want to muddy the waters since some of those specs were used as a base point. I was working (originally) with the lead guy at HRE who was using other XLR applications and then adding or deleting the desired setting I wanted.

Yes, a three piece wheel allows for the most flexibility and customization, at a price. There all more advantages too such as weight and low runout numbers.

You may want to check your original front offset comment. I believe the wheels all carry the same part number, on a given car, and have the same offset front to rear. I know mine do. It is even stamped on the wheel.

I'm hoping you will share your specs and pictures once you find a good working setup. The forum is all about sharing information. I would also be interested in your costs. This is something that has been a long term discussion here and many mistakes made. Did you measure the radial or lateral run out?

 

[Phrede]

Agreed. 35-series is perhaps the most extreme route I would go with on a XLR using after market wheels. As you know, going 35-series is used because of the increase in wheel size and keeping the same diameter. Granted, comfort takes a back seat.

The biggest challenge I found was finding a good performing tire available in the correct size while matching the revs/mile within 1 or 2%. Getting everything to match and fit is a task.

 

[madcurl]

The biggest challenge I found was finding a good performing tire available in the correct size while matching the revs/mile within 1 or 2%. Getting everything to match and fit is a task.

For me the problem is finding a run flat tire for 19/20 combo. If you're willing to go beyond the stock size there seem to be no problem finding tires that are within the 1-2% if the OEM is 27.4 and for a 275/35/20 is about 27.7 in diameter if used on all four corners.

 

[Phrede]

For me the problem is finding a run flat tire for 19/20 combo. If you're willing to go beyond the stock size there seem to be no problem finding tires that are within the 1-2% if the OEM is 27.4 and for a 275/35/20 is about 27.7 in diameter if used on all four corners.

That's where we differ. I will not consider runflats. My OEM tire had a 27.0" diameter/745 rev/mile on the rear. In theory a 275/35-20 has a diameter of 27.6 or 730 rev/mile. Actual dimensions will vary some from tire model to model.

 

[madcurl]

Here's a example of the HRE 543R 20x11 weight prior to shipping.

new weight; 20x10 w/chrome outer lip.
I finally got around to getting the last of the 275/35/20 tire today (2-275/35/19 & 2-275/35/20)

 

[madcurl]

As you can see that the 275 are a bit stretched (rolled) thus allowing for clearance of the outer fender. I still need to drive around for several miles to make sure there's no clearance issues.

Front: 19x10, 275/35/19 PZero run flat.


Currently, my tire technician is on a mini vacation and won't be back until the middle of the week.

 

[standby-V]

255/35/20" tires

Way back in this thread I gave erroneous info on tire size and need to set the record straight so others will not be mislead. I reported that I had 275's on my V but in fact I meant 255/35/20" and any taller or wider would tear up the inside of the inner liners in the rear only. I apologize for the error........my bad.

 

[Phrede]

Way back in this thread I gave erroneous info on tire size and need to set the record straight so others will not be mislead. I reported that I had 275's on my V but in fact I meant 255/35/20" and any taller or wider would tear up the inside of the inner liners in the rear only. I apologize for the error........my bad.

A 255/35-20 is the same outer diameter and width as 255/40-19, the stock rear size.

 

[standby-V]

That's good to know, moving to 20" rims makes the car look so much better. I ordered four new sticky Dunlop's today and will have them installed tomorrow for a total of $680, even though I have another years worth of tread, I notice the hardness of three year old tires, especially for grip come the rains in winter. While at Just Tires, I asked if they had any tires with the thin red circle because it looks so good on the super cars. Hey, what the hey ours are super cars. I have a curb bead that I could have dyed or painted. Does anyone know how to dye or paint that bead red on rubber that will last?

 

[Phrede]

That's good to know, moving to 20" rims makes the car look so much better. I ordered four new sticky Dunlop's today and will have them installed tomorrow for a total of $680, even though I have another years worth of tread, I notice the hardness of three year old tires, especially for grip come the rains in winter. While at Just Tires, I asked if they had any tires with the thin red circle because it looks so good on the super cars. Hey, what the hey ours are super cars. I have a curb bead that I could have dyed or painted. Does anyone know how to dye or paint that bead red on rubber that will last?

http://www.summitracing.com/parts/shw-ht200/overview/

 

[standby-V]

Tire clearance

WOW, that was too easy, Thanks Phrede

 

[Popbigguy]

A 255/35-20 is the same outer diameter and width as 255/40-19, the stock rear size.

But, about a 1/2" shorter sidewall ht. on the tire.

 

[madcurl]

While we're on the subject of "clarification" I just wanted to add that the specs given in this thread are from HRE (not me). These wheels were custom made according what the customer wanted.


The front #s;
19x9.5, ET52, Rims 8.0/1.5

The rears #s;
20x11.0, ET61, Rims 9.0/2.0

The tires sizes I've decided to use are P-Zero run flats; 275/35/19 (f) and 275/35/20 (r). 19x10 (f) and 20x10 (r)
(you can check TireRack for the specs on the tires being used).




HRE records every wheel they've made and some older records dates back before they stated using computers to log-in the specs. It is these references or "specs" that I'm now adding/subtracting on my XLR. The reason "why" I originally didn't want to post the "specs" was because the wheels were custom ordered thus not OEM so there was no need to muddy the waters. That said, once I get around to driving the XLR around a bit (testing the waters) and if there's no sign is problems you can then (if you like) use the new specs I'm using or add/subtract accordingly.

Like I said originally, I don't like the 235/50/18 nor the XLRV sizes. Comfort will have to take a back seat on this one for I've never been the type of guy who owns touring tires. Besides, several members here are sporting Corvette wheels on their XLR so my combination can't be worst than a Corvette using 285 in the rear. Seriously, the XLR (or V for that matter) has aggressive stance, but upon looking at the profile from the rear it reminds me of a body builder with skinny legs. Big on top, but thin on the bottom. I've seen others using 22" but with 255 tires. I wanted something with a wider track w/o clearance issues. The upside to using the run flats is perhaps better protection during a flat due to the hard side walls supporting the weight of the car. Who knows, maybe there might be a measure of protection if you hit a "minor" pot hole.

Enough of that, let's see the clearance on the inside;

I'll try and take more pictures shortly, but coming back from a vacation, tire technician on vacation, and back to work the wheels aren't on the top of the list.