If you are experiencing the problem while road racing, then it doesn't necessarily mean you need wider tires. However, that would certainly be one option.
Do a search here and pull up information on balancing your brakes (much has been written on this subject) You may find that you need to transfer some brake bias to the rear brakes or use different pads to get the best result.
If you lower the ride height appropriately you can end up with more "downforce" or weight on the front tires while braking and find that result to be a lot more effective.
Larger tire sizes may cause a problem with clearance on the fender wells if you lower the car enough to get the downforce you want for braking and cornering ability.
Stiffening the suspension, changing the ride height, adjusting the brake bias, and going with larger tire sizes are all part of an overall "package" that need to be worked out through specific advice and testing.
Check with people at ViperDays who have a set up like yours and see what they do. Everybody has to find the particular set up that works for them.
The only other sound advice is to listen to Fred and get some instruction in threshold braking. We've all been to enough schools to know there's more to learn.
Good luck,
