HRE 543R: Testing clearances on 2007 XLR

[Phrede]

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

Yes, the sidewall is very close to 1/2" shorter on each side or 1" overall. This allows for the 1" larger wheel diameter with no change in the tire OD.

Usually a shorter sidewall will result in less sidewall flexing for "tighter" performance and a "stiffer" ride. There is also a higher risk of rim damage from road hazards. Additionally, the unsprung weight of the bigger wheel/shorter sidewall is usually less, improving performance. I'm not sure how much the weight difference really matters with our dynamic magnetic suspension. I would expect a bias is built into the software tuning for the stock unsprung weight.

There is a styling component as well. Some prefer the look of the larger wheel.

Another thing to consider is tire availability for a given tire size. Not all models of tires are available in all sizes. There may a tire that fits your needs available in a 20" diameter that is not in a 19", or the otherway around.

Up to a point, it's all a matter of personal preference and where you want the balance of comfort, performance and styling to be on your own car. The further you vary from stock the higher the risk going out of the engineered "safe zone".

 

[richardyoo]

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 have 285/30/20 in the rear of my car... additionally I lowered the ride height about an inch. I've been riding this way since 2009 I haven't had any problems... my first set of tires were Michelin pilot sport 2's... and I just put on a new set of Michelin pilot super sports last month.

If you are having rubbing issues I have to think that your wheels are not fitted correctly for a wider tire... when shopping for wheels I had called up D3 and had them spec and build the wheels for me via Forgeline and I haven't had any clearance issues with larger tires nor the larger brakes I put on.

 

[Phrede]

I have 285/30/20 in the rear of my car... additionally I lowered the ride height about an inch. I've been riding this way since 2009 I haven't had any problems... my first set of tires were Michelin pilot sport 2's... and I just put on a new set of Michelin pilot super sports last month.

If you are having rubbing issues I have to think that your wheels are not fitted correctly for a wider tire... when shopping for wheels I had called up D3 and had them spec and build the wheels for me via Forgeline and I haven't had any clearance issues with larger tires nor the larger brakes I put on.

Can you share the wheel specs? What are you running in the front? How about a pic of the rear showing the outer tire edge and the fender lip? The 285/30-20 is about a 5/16" or about 1.1% shorter than stock overall, not so bad.

 

[madcurl]

I have 285/30/20 in the rear of my car... additionally I lowered the ride height about an inch. I've been riding this way since 2009 I haven't had any problems... my first set of tires were Michelin pilot sport 2's... and I just put on a new set of Michelin pilot super sports last month.

If you are having rubbing issues I have to think that your wheels are not fitted correctly for a wider tire... when shopping for wheels I had called up D3 and had them spec and build the wheels for me via Forgeline and I haven't had any clearance issues with larger tires nor the larger brakes I put on.

Thank you for your words of encouragement for I searched and searched on this site, but it wasn't until you posted that I reviewed your previous threads in the technical section. I must say I really like those custom three piece wheels on your XLRV. You know, we should start a thread specifically for custom wheels for it eats up a lot of time searching through threads related to the subject.

That said, if you're not having issues with the 285/30/20 in the rear of your XLR then neither will I (provided my ET are similar to that of yours). HRE has been very helpful in my quest for the widest wheel width. However, since I've already mounted the 275 (front and rear) I will no doubt have to use them until they wear out, but it's nice knowing I can move up to a larger tire size in the future. BTW, I have a set of custom HRE wheels similar in style like the ones you have, so I'm biased towards you.

I hope you don't mind, I wanted post your pics here on this thread for visuals. I saw your pictures in another thread but there wasn't any close-ups until I found theses;

Richardyoo pics:

Now, that's what I'm talking about!

 

[madcurl]

Ah man, this is unbelievable!

 

[richardyoo]

Can you share the wheel specs? What are you running in the front? How about a pic of the rear showing the outer tire edge and the fender lip? The 285/30-20 is about a 5/16" or about 1.1% shorter than stock overall, not so bad.

The fronts are 20" x 9" and the rears are 20" by 9.5"

On the front I have 255/35/20 pilot sport 2's...

As far as tire height - I've reprogrammed my ECM to adjust for the tire size difference so the speedo is spot on.

 

[Phrede]

The fronts are 20" x 9" and the rears are 20" by 9.5"

On the front I have 255/35/20 pilot sport 2's...

As far as tire height - I've reprogrammed my ECM to adjust for the tire size difference so the speedo is spot on.

Do you know the offsets?

 

[richardyoo]

Do you know the offsets?

I don't remember - it was a few years ago... I had D3 spec it so they were doing the math... all I remember is that I had them make sure they'd clear a future big brake kit... since then I've installed the Z06 brakes, and then upgraded them to a custom powder coated rotora kit with 2-piece rotors... I haven't had any issues with clearing the fenders with the tires, or the brakes with the wheels...

 

[madcurl]

I don't remember - it was a few years ago... I had D3 spec it so they were doing the math... all I remember is that I had them make sure they'd clear a future big brake kit... since then I've installed the Z06 brakes, and then upgraded them to a custom powder coated rotora kit with 2-piece rotors... I haven't had any issues with clearing the fenders with the tires, or the brakes with the wheels...

I saw the Z06 brake upgrades in the technical threads. Can you please post more comments regarding the upgrade to a 2-piece rotors w/pics. The HRE I currently have used the Ebear upgrade brake system for the Corvette so they were made to clear 14" rotors. I too plan on upgrading. I hope you don't mind me posting your pictures in this thread.

 

[richardyoo]

I saw the Z06 brake upgrades in the technical threads. Can you please post more comments regarding the upgrade to a 2-piece rotors w/pics. The HRE I currently have used the Ebear upgrade brake system for the Corvette so they were made to clear 14" rotors. I too plan on upgrading. I hope you don't mind me posting your pictures in this thread.

I don't have any photos of the new brakes - I was in a rush getting ready for the Houston 1/2 mile run so I was focused on getting them on the car. I'll try to shoot some the next time I have the car off the ground and the wheels off.

They are a rotora 6-piston front and 4-piston rear... 14" rotors front and rear... I used the rotora aluminum hats, but replaced the rings with Zinc-coated slotted and dimpled from Adams rotors.

Incidentally Rotora got bought by Stoptech if I recall correctly. the replacement rings I have are stoptech rings and they fit on the rotora hats.

I ended up using Hawk HPS+ pads front and rear... and man do these brakes grip - I was street racing stop light to stop light with this z06 vette and I got it up to about 70mph in a 35 zone I hit the brakes to slow down and they immediately locked up and the ABS kicked in... I never had that happen with the Z06 or the stock V-series brake set up. Its just awesome.

 

[madcurl]

Ah man 14" up front & in the rear; that's sweet! While we wait for pictures with the wheels off the car can you take pics with the wheels on the car? I like to see those big brakes behind the wheel. Oh yeah, my guess is you saved a few pounds using the 2-piece rotor, right? Or did it even out using the big brakes?

 

[madcurl]

I called D3 here in CA yesterday regarding brakes, exhaust, and body kits they offer. I might be interested in getting their brake set-ups Brembo or Rotora (I haven't decided on which one). Either way, it's a costly set-up, but a must have if you have wheels that exposes the backside. The Brembo are the higher end and the colors are; Silver, Black, Red, and Yellow (didn't ask about the colors for Rotora). The rep is sending me the info via email. The shop is located just outside Long Beach, CA in Signal Hill, CA which is only a 2-hr drive for me if I time it right. LA traffic.
As for the wheels; the wheel and rear aren't in the same location, so I haven't gotten around to driving the XLR to test for possible issues. My tire technician had no problem in mounting the 275 on the 20x10 wheel using the tire sensor (cost $30). The tire is some what smaller in width so it "rolls" inward and it looks to be the same the "roll" using the 235/50/18 mounted on the after market Breyton 18x8 wheels that are currently on the XLR, so my guess it will be the same results with the 275. I have a couple of days off next week to test my results. My vacation, tire technician's vacation, and his location up north and car down south isn't the best game plan when it comes to testing wheels.

 

[madcurl]

Well, I arrived down south a bit too late, but the first thing early in the morning is to test the tire for clearance and to drive the car around town for a few miles. Out of pocket $431 x4 =1724 or close to $1900 for (4) tires after mounting and balancing. I did take a few pics of the 275/35/20.

Normally, I run bigger tires on my Fiero N* LOL, but for now this size will have to do until I have the body widened out. I like that D3 wide body kit!

The tire sits a bit beyond the bead, but will see on Wednesday.

HRE provided me with free center caps. I might get the bullet caps later down the road.

Until Wednesday (I hope).

 

[madcurl]

So far-so good; at least for the inners.

I measured both side (lt. 18x8 & rt. 20x10) and it appears that both side are about the same. The P-Zero has rolled corners just like the Michelin. There's a smaller P-Zero with 10.9 width and the one I have is 11.2 width. I didn't notice it until the last minute, so I need be I can have TireRack replace the current tire, but for right now I'm happy with it. More pictures in a minute for some of them are upside down.

 

[madcurl]

 

[madcurl]

 

[madcurl]

The previous owner had after market wheel that stuck outside the body just a tad bit and it appears the HRE 543R are just about the same.

Comparison pics;

I emailed HRE the comparison pics and Nick said that "it's a slam dunk right there-if there's no rubbing." One thing is for sure. I'm not going back to the cheaper style wheels. Just them as "shop rollers" or winter usage.

 

[madcurl]

After market wheel;

HRE 20x10 wheel.

Conclusion: about the same.

 

[madcurl]

Okay, I've been driving in and around town looking rather silly with one tire that's different from all the rest. However, so far I have to report that there are no problems. No rubbing, no visible signs on the wheel liner while on the highway (even in the tight turns), on bumpy roads, and while crossing bumpy railroad tracks to which I'm going about 5 miles an hour like I normally do.

Granted, I don't have a overweight girlfriend so the tire hasn't been truly tested and the chances are it probably will never be , but I did have the spare in the trunk so that at least weighs 50 to 60 pounds. I email hre and it will take probably 4 to 6 weeks for the remaining wheels to arrive.

 

[madcurl]

Update: The remaining centers are being cnc machined/powdered coated and completed by this Friday. HRE has the specs and I will post them once I get the remaining wheels back from HRE. HRE has been a great help in getting me what I wanted and it looks like I'll be at SEMA with the XLR this year. I had plans on taking the other N* Fiero, but this time I'll bypass the exotic sport for luxury sport. Once the wheels arrive then I'll have them mounted which should take a week. Now I have to pay for the Corvette calipers and rotors which should look sweet behind the HREs.

19x10, 275/35/19 P-Zero run flats

20x10, 275/35/20 P-Zero Run Flats.

Also, I got my plates back from the DMV and I must say, " I do like them." I decided to keep the plates "simple-stupid." Just the name of the car followed by the number sequence the car was made for that year.