I have an 07 GT Premium Convertible, just turned 60K miles, stock suspension and wheels. When the tires wear out I was thinking about going with 19" or 20" staggered. I bought this for my wife because she wanted a convertible. It's been well cared for with no rust not even underneath. It's just something we play around with. She has her DD and so do I.

1. Those of you that have staggered wheels. Do you rotate them side to side or not at all?
2. How is the ride compared to stock with the shorter tires and larger wheels? The reason I ask is because this thing rides a little rough already.
3. Is there something I can do to make this thing ride smoother?

I do most of my service work at the local ford dealer which I been using for years now and trust them 100%. They haven't ripped me off yet anyway and they had plenty of chances. I had them check out the suspension and they said, the suspension and everything else looks and checks out just fine. They said it's suppose to ride like that (rough like that).

 

While I don't have any wheel sets that are staggered in the conventional sense of the term, one of the sets for my '08 GT had to run significantly different offsets front vs rear (nearly 20mm different IIRC), so it ends up being subject to the same difficulties with the usual 4-tire tire rotation schemes.

1) I do rotate them side to side. And so far, I have swapped the front tires onto the rear wheels and vice versa (once). Full disclosure, this is my road course HPDE setup, so the side to side stuff happens before every event as part of getting ready for it . . . IOW, far more often than you'd ever need in street duty. I may or may not wear the tires out before they need another front-rear remount and rebalance.

Obviously if you were to choose a staggered setup, any front-rear swap would be a non-starter.

2) Going up in wheel size normally involves picking lower-profile tires in order to maintain the same tire OD (and speedometer accuracy). And yes, shorter sidewall tires do tend to ride a bit firmer. The specific tires matter, since not all tires in a given size ride provide equally good ride quality. Spend some time browsing the tire ratings charts on Tire Rack looking at their "Comfort" column. But don't pick a tire on ride comfort alone - its wet and dry performance ratings are ultimately more important - use Comfort more as a tie-breaker to separate your choice out from a number of tires having comparable performance.

For a staggered setup, you really do want to have both the front and rear tire sizes be the same tire make and model. Mixing tire models can result in unexpected handling behaviors.

3) I'd use the willingness to invest in a different set of wheels and tires to pick a combination that gives ride quality priority over ultimate performance. Tires are your car's first line of defense against road roughness making it through to the seats. What size tires are on the car now?

As a general comment, you can favor ride quality by choosing wheel widths that are down around the minimum recommended width for your proposed tire size - as an example, should you decide on 255/45-18 tires (same OD as OE and actually the OE front tire size for the GT500), you'd want wheels that were 8" or maybe 8.5" wide (rather than 9.5" wide as used on those GT500's). Narrower wheels provide more sidewall curvature (aka "bulge") that makes them more flexible against bumps. And since the 255/45 tire is rated for more load than the GT's OE 235/50-18 tire, you can legitimately run them at a couple of psi lower inflation. If you rarely or never load up the trunk or carry rear seat passengers who aren't small children, you could take another psi or two out of the rear tires. Ride comfort seems to be more a function of the rear tires and suspension than the fronts.

The next item would be the car's shocks and struts. If they're the originals, chances are that they're not doing much and could be letting the car bottom its suspension out on the bump stops too often. If they're new, like really new, there could be some friction/stiction going on with the seals in them that will wear itself in after a while.


Norm

 

I have the stock 235/50-18 and stock suspension. So, new shocks and struts or a whole new shock/strut/spring setup? A little lower maybe?

I was thinking about going 265/40-19 x 8.5 fronts, 285/35-19 x 10" rear. Up one size couldn't hurt the ride quality that much could it?

Thanks for your input, Dan

 

Heh, funny thing is that the tires I now run on my '08 are in fact 265/40 (all around) for extended periods of street-only driving, and 285/35 (again, all around) for HPDE and brief periods of street driving in between events. I doubt that your proposed 19's would ride much different from the same widths/profiles in 18's (mounted on the same 8.5" and 10" wheel widths). Chances are your 19" setup would ride somewhat better than my car does with either of the sets it now has, simply because my 265's are mounted on 9.5's and the 285's are on 11's, a full inch more wheel width in each case.

Even though my car's suspension has been firmed up somewhat, I think it still has a decent ride for a stick-axle car, as long as I don't have the shocks and struts dialed up too far toward full firm on the street. My wife is entirely OK with the ride with them dialed back closer to full soft. I should mention that although we're both in our early 70's, our ride vs handling preferences have always run more toward 'handling performance with a firm ride' rather than 'relaxed cruising with a softer ride'. Our current "family sedan" is a 2019 WRX, if that helps. Yeah, we're probably oriented more toward performance driving than most people.

As far as suspension mods go, I think you'll be best off to limit the changes to firmer sta-bars and better shocks & struts. I think that would net you the most improvement in handling and driving satisfaction at the least expense in terms of ride quality. With good shocks and struts you may not even notice any deterioration in ride, once the new dampers have "broken in".


Norm

 

Thanks, still weighting my options, Thats a lot of, good info Norm. Thanks for your input!

 

I have run a lot of staggered set ups in years past but currently don't have any staggered. I tend to avoid pot holes and burn outs and I watch tread wear across the tires and I watch my pressures. I don't think I've rotated tires just to rotate tires on a car of mine ever since starting to drive in 1970 through about 15 or more cars & 4 pickups. I did align my '07 F-150 after lowering it in 2011 ... did it myself using levels and trig.

I can recall taking our station wagon to Sears to have the Michelin Radial-Xs rotated for my mother just before a trip out west, had front end aligned at the Plymouth dealer too, first gas stop was still in state, checking tires like Dad used to do (Dad passed in '69) , fronts were wore to cords on outside edge so we had to get the front re-aligned and buy two tires to finish our vacation. Put two cheaper (not Michelin) bias ply tires on front against local advice (I"t'll be OK" I said, and it was OK).

In a career of 31+ years as a trooper, and those assigned 14 cars I did sometimes replace just two on an axle and then put the newest on the front axle and the most worn on the rear as the car set in the road better at speed that way. Not even on the state's dime did I ever rotate just to rotate. I did occasionally have to have a police car aligned after an incident of some sort. Even as a toad, I watched wear, got alignments if needed (rarely) and usually it was rear tires that wore fastest.

When more roads were dirt or gravel, when roads had frost heaves and holes and not so nice RR crossings, when people forded creeks, alignments were more common as front end parts wore faster and tires often bias ply wore out faster or just blew.