295/35/19 x 335/30/20 with Custom cut wheels, Need advice please

merkyworks

Well-Known Member
Established Member
Joined
Apr 5, 2016
Messages
980
Location
Houston
Going to be ordering some Signature SV103 1-piece monoblock wheels and I need some help with finalizing size and offset. Car is daily driven and at stock SVTPP height. My goal is to stay as close as possible to stock sidewall heights so ride quality doesn’t suffer, yet stuff more tire under the car for better traction/handling. However I don't want the car to look like a lifted 70's muscle car or have tires/rims that stick out way past the fenders. I want it to look like this could have been a factory rim/tire package Ford/SVT offered.

Rears
In researching I found two people running MPSS 335/30/20’s. DutyCalls on 11.75” wide wheels with 65.5mm BS and BITDIFFERENTSVT on 12.00” wide wheels with 62.1mm BS. The inner lip on both rims is basically the same distance from the mounting face, so the 12.00” wide wheels stick out a 0.25” more toward the fender. It’s hard to tell from pics which would be the better width to go with. Does anyone have any advice?
Also running 325/30/20 in MPS Cup 2’s is not something I want to do because the compound is too soft and longevity would be abysmal.

Fronts
I really couldn’t find any information on front wheel/tire combos so I’m really lost here. Thinking MPSS 295/35/19’s on a 10.00” wide with 37mm BS or 10.50” wide with 43mm BS. I used Alcoas fronts as a ref for the BS but maybe that's a bad idea, I have no clue. Also I'm not sure which width I should go with, any advice is greatly appreciated.
This may be stupid but is there even enough room to maybe run a MPSS 305/35/19, has anyone even done this, would doing this even be a good idea?
 

12boss302

Active Member
Established Member
Joined
Feb 3, 2016
Messages
193
Location
Las Vegas
A 305 in the front? I don’t see how that’s a good idea. And you’re tryif to fit all of this without a wide body?
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
I'm running a 325/30-20 on an 11" wheel with 62mm backspacing. On the front, I'm running a 285/40-19 with 44mm offset. There's not a lot of clearance between the cross section and the strut. Bear in mind that's the stock SVTPP and only 9.5" wide. The cross section would increase on a wider rim.
 

DutyCalls

Active Member
Established Member
Joined
Feb 2, 2009
Messages
569
Location
North Bay, Ontario canada
I don't know if I would do a 335 on a daily driver. When I stated I only rub occasionally, you need to consider I only put about 5000kms annually.

There is not alot of room for error....My tires occasionally rub the wheel well. For an experiment, i ordered some 3mm spacers (.118) to see if that would fix my problem. Surprisingly, it made a huge difference visually...it pushed the tires out past the fenders enough to look bad, and they were now rubbing the outer fender. I would them rather hit the wheel well, so i removed them.

Visually, they are incredible. They definitely look wider in person than in pics and even better when seen from behind while the car is driving. The tires tuck in so far on these cars most people don't even realize how wide they are until the look under the car.

I don't know if this helped you or not..lol
 

merkyworks

Well-Known Member
Established Member
Joined
Apr 5, 2016
Messages
980
Location
Houston
Hmmm, guess I'm being too ambitious for how much tire I can fit under the car.

I'm running a 325/30-20 on an 11" wheel with 62mm backspacing. On the front, I'm running a 285/40-19 with 44mm offset.
285/40/19 is a 28" tall tire with a 4.5" sidewall so the rear has to be a 315/35/20 at minimum or it looks off. I have read in other post you plan on switching to 20's in the front and eventually run 285/35/20's. Is that still your plan? Running a 315 or 325 in the rear will require a 11" wide rim at minimum but wondering if a 11.5" would be a better option. Would the slightly wider wheel help the 315 not bulge as much and let the sidewall sit a little flatter? Your 20x11 with a 8mm spacer puts the BS at 61/62mm's and you said the 315's were still under the fender. How much more could they have pushed out before they were flush with the fender?


Cause there really aren't a lot of options for 19" tires it looks like I need to go 20" tires on all 4 corners.

Option A is my first pick cause I can run MPSS. Option B is a possibility but then I have to run Cup 2's and past the durability I have read they are scary in the rain, anyone that has these care to comment? Dunlop's are stupid expensive so they are out.
Thoughts?
Tire Sizes1.jpg

For front wheel offset I did some measuring, stock 265/40/19's and 44mm offset wheels. Outside fender is 15-16mm from the tire. I wasn't able to measure the distance between the tire and the strut but I would say it's in the 15-16mm range as well.
IMG_7852.PNG IMG_7843.jpg

A 20x10 with 39mm BS should put the tire flush with the outside fender and not have any interference issues with strut. It's possible maybe to run a 20x10 with 44mm BS but that might be to close to the strut?
Front Wheel.JPG
Front Wheel2.JPG
 

LuuisHernandez

Active Member
Established Member
Joined
Dec 15, 2015
Messages
565
Location
California
I’m sure you can possibly fit a 335 but you’d need a pretty high offset. At least 60s.


Sent from my iPhone using svtperformance.com
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
Yes, I am putting on a set of True Forged wheels which are 20" diameter. I will likely put on 285/35-20s up front at some point, but the wheels came with a perfectly good 275/35-20 MPSS, so I'll probably use that for a while. My experience has shown me that the cross section width will probably be about the same as a 285 with a narrower tread width. If the weather is not too bad, I'll take some measurements on the clearance with the strut on the stock SVTPP wheel and the 285/40-19 I have on it now. I haven't touched the car in a month with a back strain and a really bad cold.

I'm also going to add a wider hoop to the rear wheel and will end up with 11.5" of wheel width. I know it's going to increase the cross section width from my 11" wheel, but will give me the same offset. I'm hoping the decreased diameter, and higher spring rates will minimize contact with the inner fender. In all likelihood, the 325 mounted on the 11.5" wheel width should be pretty close to the 335 on a similar sized wheel. Here's an example why. This shot is my 325/30-20 and a 295/35-20, both on 11" wheels. If there is any difference is a very small fraction.

295 vs 325 on 11s.jpg


Here's something to consider. While you may look at measured cross sections on Tire Rack or manufacturer's websites, that spec is based on the tire mounted on a particular width wheel, usually identified in the spec. You should consider that the cross section width will increase or decrease with a wider or narrower wheel, respectively, to the tune of approximately .2"-.25" for every .5" change in wheel width. Those fitment calculators do not take that into consideration, but you can fudge the tire size to get the correct width. It's also easier to correct for too much offset than too little with spacers. There's not a lot you can do with too little offset.

As for SC2s in the rain, I think they're probably better than some other competition based tires. While I certainly don't plan to drive in rainy weather, living in Louisiana, you just never know when you could get caught in a shower. I will just to looking for them to get me to a safe place. I don't see a whole lot of difference in the thread pattern between the MPSS and SC2, but the compound is certainly softer.
 

Bad Company

Well-Known Member
Established Member
Joined
Sep 13, 2012
Messages
1,943
Location
N/A
I'm running a 285/35/20 on a 20 x 10 wheel with a +48mm offset. With these there isn't any room left for clearance between the strut and tire to speak of.

To go larger than this on the front, you need to purchase special struts that have a offset mounting bracket for the spindle. Griggs and CorteX Racing sell them. The down side of this mod is it is designed for 315 tires on 18" wheels. You must remember as you go wider with the same sidewall ratio the tire also gets much taller. The height of a 305 or wider 20" tire starts having other interference problems inside the fenderwell area of the car. This is why the offset struts are designed for 18" wheels

The 285/35/20 I believe is the largest 20" tire you'll fit on these cars on the front. With these I have also installed a set of Roush steering rack travel limiters to stop the tire from hitting the inside area of the fenderwell at full lock.
 

merkyworks

Well-Known Member
Established Member
Joined
Apr 5, 2016
Messages
980
Location
Houston
Yes, I am putting on a set of True Forged wheels which are 20" diameter.

What offset are they?

I'm also going to add a wider hoop to the rear wheel and will end up with 11.5" of wheel width. I know it's going to increase the cross section width from my 11" wheel, but will give me the same offset.

I'm a little confused with the offset you have run with different spacers/tires, is this correct summary correct.
SVTPP wheel 20x9.5 with offset +50mm , added 1.5" to rim which made offset +69mm. 315's to close to the frame, added a custom 8mm spacer which gave the wheel a +61m offset. This worked okay but you "still experiencing some rubbing under off-camber axle articulation negotiating driveway entrances. With the 8mm spacer, all of the tire is still under the fender."

So on 315's if you could have run a bigger spacer like a 10mm (+59mm offset) or 15mm (+54mm offset) would the tire still have fit under the fender and you not had the frame rub issues?

When you go to an 11.5" rim with a .25" spacer your offset will be +69mm, is that correct? If so your outer rim will be roughly the same location as when you had a 11" rim with +61mm offset but now your .5" closer to the frame. That seems like it would put the tire pretty close to the frame, are you going to have issues with 325's rubbing on the frame?

You should consider that the cross section width will increase or decrease with a wider or narrower wheel, respectively, to the tune of approximately .2"-.25" for every .5" change in wheel width.

For a 325/30/20 Cup 2Tirerack states the following...
Capture1.JPG
Since you have these mounted on a 11" rim your current cross section is around 12.8"-12.75", however when you go to 11.5" rim your cross section will then be the advertised 13". Is this correct?

For a 315/35/20 MPSS Tirerack states the following...
Capture.JPG
On a 11" rim the cross section is 12.6" but if this was to be mounted on a 11.5" rim the tire cross section would become 12.8"-12.85". Is this correct?
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
What offset are they?

Wheels as delivered were 9.5x20 for the front with a +37mm offset, rears are 11x20 with a +57mm offset. I'm taking the inner rear hoop and putting it on the front wheel to end up with a 10x20 with a +43mm offset and I bought a hoop for the rear that will widen the rear width to 11.5" with a resulting offset of +63mm.

I'm a little confused with the offset you have run with different spacers/tires, is this correct summary correct.
SVTPP wheel 20x9.5 with offset +50mm , added 1.5" to rim which made offset +69mm. 315's to close to the frame, added a custom 8mm spacer which gave the wheel a +61m offset. This worked okay but you "still experiencing some rubbing under off-camber axle articulation negotiating driveway entrances. With the 8mm spacer, all of the tire is still under the fender."

Yes. I have always verified fitment by removing the rear spring and jacking up the rear up to determine how close the fender was to the inner fender. With a 28.8" diameter, and a cut bump stop, if the tire stuck out to far, the fender lip would contact the tire. It tucked with both the 8mm spacer and the 315 and the 1/4" spacer and the 325.

So on 315's if you could have run a bigger spacer like a 10mm (+59mm offset) or 15mm (+54mm offset) would the tire still have fit under the fender and you not had the frame rub issues?

I think the sidewall would contact the inside of the outer fender on a hard compression.

When you go to an 11.5" rim with a .25" spacer your offset will be +69mm, is that correct? If so your outer rim will be roughly the same location as when you had a 11" rim with +61mm offset but now your .5" closer to the frame. That seems like it would put the tire pretty close to the frame, are you going to have issues with 325's rubbing on the frame?

I won't be using spacers with the True Forged, but by increasing the width to 11.5, I'll be achieving the same offset as the widened SVTPPs with the spacer. I was running stock SVTPP front springs (~220 lb/in) and 185 lb/in rear springs. I've increased the front with dual adjustable coil overs with 380 lb/in front springs and dual adjustable rear shocks with 250 lb/in rear springs. I think body roll had more to do with my rubbing issues. I have a watts link, so I don't think the rear end is moving side to side. I can tolerate a little rubbing on off-camber driveways.

For a 325/30/20 Cup 2Tirerack states the following...
View attachment 1454095
Since you have these mounted on a 11" rim your current cross section is around 12.8"-12.75", however when you go to 11.5" rim your cross section will then be the advertised 13". Is this correct?

I"m not sure. My cross width on the 11" rim is more like 12 5/8". I can't see the cross section going to 13" on the 11.5" width, but it will something slightly less than that.

For a 315/35/20 MPSS Tirerack states the following...
View attachment 1454094
On a 11" rim the cross section is 12.6" but if this was to be mounted on a 11.5" rim the tire cross section would become 12.8"-12.85". Is this correct?

The cross section of the 315 on the 11" rim was the same as the 325 on the same wheel, 12 5/8", but rounded would be 12.6". I would expect them to be the same width on an 11.5" rim which I'm guessing would be ~12.85 +/-. I've never measured by widened wheel to determine they are exactly 11", so that could be a variable. Michelin also has a thick area near the wheel for wheel protection. That may also come into play on a wider wheel as being the widest part of the tire.
 

Users who are viewing this thread



Top